Comparison Nokia 3310 2017 Dual Sim 0 B vs Nokia 150 2 SIM

The type of removable memory card slot.

In itself, the presence of such a slot allows you to expand the built-in storage of the device. This feature is especially useful given that large built-in drives are quite expensive — noticeably more expensive than removable cards. At the same time, we note that the design may provide certain restrictions on working with memory cards — for example, the inability to install an application on this card. These restrictions are usually directly related to the operating system used. And the speed of those cards is noticeably lower than that of the built-in storage. Therefore, there are phones without a memory card slot, so that there is nothing third-party in the operation of the device.

Separately, we note that in some devices for 2 SIM-cards, the slot for a memory card can be combined with a slot for a second SIM card. If you want to use 2 SIM and a memory card at the same time, you should choose a device with a dedicated slot for a memory card.

As for the types of cards, microSD cards are the most popular nowadays: they are quite compact, inexpensive and available in a variety of volume options. Some Huawei smartphones use a different standard – Nano Memory (colloquially Nano SD). Among the advantages of such cards are a miniature size (corresponds to nanoSIM), high capacity (64 GB, 128 GB and 256 GB op...tions were initially presented), as well as high speed (from 90 MB / s). On the other hand, most often they are installed not in a separate slot, but instead of a second nanoSIM card.

The largest volume of memory card with which the phone supports. For more information about the cards themselves, see "Memory Card Slot"; here we note that capacious cards often use advanced technologies that are not supported by all devices, and sometimes phones simply do not have enough power to process large amounts of data. Therefore, for the convenience of choosing in our catalog, the maximum supported volume is indicated.

In fact, there are cases when some devices may exceed the claimed characteristics. However, it is worth focusing on official data, because, if officially supported volume is exceeded, normal operation of the card is not guaranteed.

Specifications of the main lens of the rear camera installed in the phone. In models with several lenses (see “Number of lenses”), the main one is responsible for basic shooting capabilities and does not have a pronounced specialization (wide-angle, telephoto, etc.). Four main parameters can be indicated here: resolution, aperture ( high aperture optics are quite common), focal length, additional sensor data.

Resolution(in megapixels, MP)
Resolution of the sensor used for the main lens. Budget options are equipped with a module 8 MP and below, many models have 12 MP camera / 13 MP, also recently a trend towards increasing megapixels has been popular. Often in smartphones you can find the main photomodule at 48 MP, 50 MP< /a>, 64 MP and even 108 MP .

The maximum resolution of the resulting image directly depends on the resolution of the sensor; and the high resolution of the "picture", in turn, allows you to better display fine details. On the other hand, an increase in the number of megapixels in itself can lead to a deterioration in the overall image quality - due to the smaller size of each individual pixel, the noise level increases. As a result,...the direct resolution of the camera has little effect on the quality of the shooting - more depends on the physical size of the matrix, the features of the optics and various design tricks used by the manufacturer.

Aperture
Aperture describes the ability of a lens to transmit light. It is written as a fractional number, for example f/1.9. Moreover, the larger the number in the denominator, the lower the aperture ratio, the less light passes through the optics, all other things being equal. For example, an f/2.6 lens will be “darker” than f/1.9.

High aperture gives the camera a number of advantages. First, it improves the quality of shooting in low light. Secondly, it's possible to shoot at low shutter speeds, minimizing the effect of "stirring" and blurring of moving objects in the frame. Thirdly, with fast optics it is easier to achieve a beautiful background blur ("bokeh") — for example, when shooting portraits.

Focal length(in millimetres)
The focal length is a distance between the sensor and the centre of the lens (focused to infinity), at which the most clear image is obtained on the matrix. However, for smartphones, the specifications indicate not the actual, but the so-called equivalent focal length — a conditional indicator recalculated using special formulas. This indicator can be used to evaluate and compare cameras with different sensor sizes (the actual focal length cannot be used for this, since with a different sensor size the same real focal length will correspond to different viewing angles). (It is also worth saying that the equivalent focal length can be noticeably larger than the thickness of the case — there is nothing unusual in this, since this is a conditional, and not a real indicator).

Anyway, the field of view and the degree of magnification directly depend on the equivalent focal length: a larger focal length gives a smaller field of view and a larger size of individual objects that fall into the frame, and a decrease in this distance, in turn, allows you to cover more space. In most modern smartphones, the focal length of the main camera ranges from 13 to 35 mm; if compared with the optics of traditional cameras, then lenses with equivalent focal length up to 25 mm can be attributed to wide-angle lenses, more than 25 mm — to universal models “with a bias towards wide-angle shooting”. Such values are chosen due the fact that smartphones are often used for shooting in cramped conditions, when a fairly large space needs to fit into the frame at a small distance. Enlargement of the picture, if necessary, is most often carried out digitally — due to the reserve of megapixels on the sensor; but there are also models with optical zoom (see below) — for them, not one value is given, but the entire working range of the equivalent focal length (recall, optical zoom is carried out by changing the focal length).

Field of view(in degrees). It characterizes the size of the area covered by the lens, as well as the size of individual objects "seen" by the camera. The larger this field, the more of the scene gets into the frame, but the smaller the individual objects in the image are. The field of view is directly related to the focal length (see above): increasing this distance narrows the field of view of the lens, and vice versa.

Note that this parameter is generally considered important for professional use of the camera rather than for amateur photography. Therefore, viewing angle data is given mainly for smartphones equipped with advanced cameras — including in order to emphasize the high class of cameras. As for specific values, for the main lens they usually are in the range from 70° to 82° — this corresponds to the general specifics of such optics (universal shooting with an emphasis on general scenes and extensive coverage at short distances).

Additional Sensor Data
Additional information regarding the sensor installed in the main lens. This item can specify both the size (in inches) and the sensor model, and sometimes both parameters at once. Anyway, such data is provided only if the device is equipped with a high-end sensor. With the model, everything is quite simple: knowing the name of the sensor, you can find detailed data on it. The size is worth considering a little more.

The size of the sensor is traditionally indicated in fractional parts of an inch — accordingly, for example, a 1/2.3" sensor will be larger than 1/2.6". Larger sensors are considered more advanced, as they provide better image quality at the same resolution. The logic here is simple - due to the large sensor area, each individual pixel is also larger and gets more light, which improves sensitivity and reduces noise. Of course, the actual image quality will also depend on a number of other parameters, but in general, a larger sensor size usually means a more advanced camera. In advanced photo flagships, you can find matrices with a physical size of 1”, which is comparable to image sensors used in top compact cameras with fixed lenses.

The type of SIM card used in the mobile phone. The term SIM here means all types of cards for identification in mobile networks, including 3G networks, CDMA, etc. (although formally such cards may have other names). The type of such a card is primarily described by its form factor. Here are the most common options:

— micro SIM. The largest type of sim cards widely used in modern devices: its' size is 15x12 mm. It was introduced back in 2010, nowadays it is being replaced by more compact and advanced nano-SIM and eSIM. Keep in mind that a microSIM card can be made by simply cutting a larger mini-SIM to the dimensions mentioned above. However this is associated with a certain risk and requires accuracy, so it is better to contact your mobile carrier to replace the SIM card with a suitable one.

— Nano-SIM. The smallest form factor of classic (replaceable) SIM-cards is 12x9 mm. In such cards the frames are cut off almost to the very chip. This standard appeared back in 2012, but it is still extremely common. Like microSIM, a card for a slot of this format can be made by cutting a larger SIM card, but this requires extreme accuracy and is not recommended.

— e-SIM. This type of SIM card is an electronic module that is built directly into the device and cannot be replaced. To authorize in the network of a mobile carrier, you need to make the appropriate settings in the eSIM. Those m...odules are able to save several sets of settings at once, which makes it easy to switch between different carriers — no need to bother with the physical replacement of the SIM card, just change the profile in the settings. Another advantage of such modules is compactness. However, before buying a phone with an eSIM, you should clarify whether this technology is supported by your mobile carrier — even nowadays, not every network is compatible with such modules.

— nano+eSIM. An option found in smartphones with two SIM cards. The built-in eSIM module in such a device is complemented by a slot for a replaceable nanoSIM card. The features of each of these card types are detailed above. It is convenient to keep the main phone number (s) on eSIM, and use replacement cards for temporary numbers. Such scenario may come in handy if you travel abroad a lot — you can install cards from local carriers in the traditional nanoSIM slot.

Types of communications supported by the device in addition to mobile networks.

This list includes two types of characteristics. The first is the communication technology itself: Wi-Fi (including advanced standards Wi-Fi 5 (802.11ac) , Wi-Fi 6 (802.11ax), Wi-Fi 6E (802.11ax) , Wi-Fi 7 (802.11be)), Bluetooth (including the new generation Bluetooth v 5 in the form of a version 5.0, 5.1, 5.2, 5.3 and 5.4), NFC, satellite communication. The second type is additional functions implemented through one or another communication standard: this is primarily aptX support (including aptX HD, aptX Adaptive and aptX Lossless) and even a built-in walkie-talkie. Here is a more detailed description of each of these characteristics:

— Wi-Fi 4 (802.11n). Wi-Fi is a wireless communication technology that in modern phones can be used both to access the Internet through wireless access points, and for direct...communication with other devices (in particular, cameras and drones). Wi-Fi is a must for smartphones, but is extremely rare in traditional phones. Specifically, Wi-Fi 4 (802.11n) provides data transfer speeds of up to 600 Mbit/s and uses two frequency ranges at once - 2.4 GHz and 5 GHz, making it compatible with earlier 802.11 b/g standards and with more new Wi-Fi 5 (see below). Wi-Fi 4 is considered a relatively modest standard by modern standards, but it is still quite sufficient for most tasks.

- Wi-Fi 5 (802.11ac). The Wi-Fi standard (see above), which is the successor to Wi-Fi 4. In theory, it supports speeds of up to 6.77 Gbps, and also uses the 5 GHz band - it is less loaded with extraneous signals and more noise-resistant than the traditional 2.4 GHz. For compatibility purposes, a smartphone with a Wi-Fi 5 module may provide support for earlier standards, but it would not hurt to clarify this point separately.

- WiGig (802.11ad). Further, after Wi-Fi 5, the development of Wi-Fi standards, characterized primarily by the use of the 60 GHz band. In terms of maximum speed, it is virtually no different from Wi-Fi 5, however, the higher frequency increases the channel capacity, so that when several gadgets simultaneously communicate with one common device (for example, a router), the communication speed does not drop as much as in earlier standards. On the other hand, the 802.11ad signal is almost incapable of passing through walls; Manufacturers use various tricks to compensate for this shortcoming, but the best communication quality is still achieved only with direct visibility. Relatively little equipment for the WiGig standard is currently being produced, and it is not compatible with earlier versions of Wi-Fi; Therefore, smartphones usually provide support for other standards.

- Wi-Fi 6 (802.11ax). A standard developed as a direct development and improvement of Wi-Fi 5. Uses the ranges from 1 to 7 GHz - that is, it is capable of operating at standard frequencies of 2.4 GHz and 5 GHz (including equipment of earlier standards), and in others frequency bands. The maximum data transfer rate has increased to 10 Gbps, but the main advantage of Wi-Fi 6 was not even this, but the further optimization of the simultaneous operation of several devices on the same channel (improving the technical solutions used in Wi-Fi 5 and WiGig). Thanks to this, Wi-Fi 6 gives the lowest speed drop among modern standards when the channel is busy.

- Wi-Fi 6E (802.11ax). The Wi-Fi 6E standard is technically called 802.11ax. But unlike basic Wi-Fi 6 (for more details, see the corresponding paragraph), which is named similarly, it provides for operation in the unused 6 GHz band. In total, the standard uses 14 different frequency bands, offering high throughput in the most crowded places with many active connections. And it is backwards compatible with previous versions.

— Wi-Fi 7 (802.11be). The technology, like the previous Wi-Fi 6E, is capable of operating in three frequency ranges: 2.4 GHz, 5 GHz and 6 GHz. At the same time, the maximum bandwidth in Wi-Fi 7 was increased from 160 MHz to 320 MHz - the wider the channel, the more data it can transmit. The IEEE 802.11be standard uses 4096-QAM modulation, which also allows more symbols to be accommodated in a data transmission unit. From Wi-Fi 7 you can squeeze out a maximum theoretical information exchange speed of up to 46 Gbps. In the context of using wireless connections for streaming and video games, the implemented MLO (Multi-Link Operation) development seems very interesting. With its help, you can aggregate several channels in different ranges, which significantly reduces delays in data transmission and ensures low and stable ping. And Multi-RU (Multiple Resource Unit) technology is designed to minimize communication delays when there are many connected client devices.

— Bluetooth. Direct wireless communication technology between various devices. In mobile phones it is used primarily for connecting headphones, headsets and wrist gadgets such as fitness bracelets, but other methods of application are also possible - remote control mode, direct file transfer, etc. In modern mobile phones there can be different versions of Bluetooth, here are their features:

• Bluetooth v 4.0. A fundamental update (after version 3.0), introducing another data transmission format - Bluetooth Low Energy (LE). This protocol is designed primarily for miniature devices that transmit small amounts of information, such as fitness bracelets and medical sensors. Bluetooth LE allows you to significantly save energy during such communication.
• Bluetooth v4.1. Development and improvement of Bluetooth 4.0. One of the key improvements was the optimization of collaboration with 4G LTE communication modules - so that Bluetooth and LTE do not interfere with each other. In addition, this version makes it possible to simultaneously use a Bluetooth device in several roles - for example, to remotely control an external device while simultaneously streaming music to headphones.
• Bluetooth v4.2. Further, after 4.1, the development of the Bluetooth standard. It did not provide any fundamental updates, but received a number of improvements regarding reliability and noise immunity, as well as improved compatibility with the Internet of Things.
• Bluetooth v 5.0. Version introduced in 2016. The key innovations were the further expansion of capabilities associated with the Internet of Things. In particular, in the Bluetooth Low Energy protocol (see above), it became possible to double the data transfer rate (up to 2 Mbit/s) at the cost of reducing the range, and also quadruple the range at the cost of reducing the speed; In addition, a number of improvements have been introduced regarding simultaneous work with a large number of connected devices.
• Bluetooth v5.1. Update of the version described above v 5.0. In addition to general improvements in the quality and reliability of communication, this update introduced such an interesting feature as determining the direction from which the Bluetooth signal is coming. Thanks to this, it becomes possible to determine the location of connected devices with centimeter accuracy, which can be useful, for example, when searching for wireless headphones.
• Bluetooth v 5.2. The next update after 5.1 is Bluetooth 5 generation. The main innovations in this version are a number of security improvements, additional optimization of power consumption in LE mode and a new audio signal format for synchronizing parallel playback on multiple devices.
• Bluetooth v 5.3. The Bluetooth v 5.3 wireless protocol was introduced at the dawn of 2022. Among the innovations in it, they accelerated the process of negotiating a communication channel between the controller and the device, implemented the function of quickly switching between the operating state in a low duty cycle and a high-speed mode, and improved the throughput and stability of the communication by reducing susceptibility to interference. When unexpected interference occurs in Low Energy mode, the procedure for selecting a communication channel to switch from now on has been accelerated. There are no fundamental innovations in protocol 5.3, but a number of qualitative improvements are evident in it.
• Bluetooth v5.4. Protocol version 5.4, which was introduced at the beginning of 2023, increased the range and speed of data exchange, which is well suited for use in applications that require communication over long distances (for example, smart home systems). Also in Bluetooth v 5.4, the energy-saving BLE mode has been improved. This version of the protocol uses new security features to protect data from unauthorized access, has increased communication reliability by selecting the best channel for communication, and prevents communication losses due to interference.

- aptX support. aptX technology was developed to improve the quality of sound transmitted over Bluetooth. When transmitting sound in a regular format, without aptX, the signal is compressed quite heavily, which affects the sound quality; This is not critical when talking on the phone, but it can significantly spoil the impression of listening to music. In turn, aptX allows you to transmit an audio signal with virtually no compression and achieve sound quality comparable to a wired communication. Such features will be especially appreciated by music lovers who prefer Bluetooth headphones or wireless speakers. Of course, to use aptX, both your smartphone and external audio device must support it.

- aptX HD support. aptX HD is a further development and improvement of the original aptX technology, allowing you to transmit sound in even higher quality - Hi-Res (24-bits/48kHz). According to the creators, this standard allows you to achieve signal quality superior to AudioCD and sound purity comparable to wired communication. The latter is often questionable, but it can be argued that overall aptX HD provides very high sound quality. On the other hand, all the advantages of this technology become noticeable only on Hi-Res audio - with quality 24-bits/48kHz or higher; otherwise, the quality is limited not so much by the characteristics of the communication as by the properties of the source files.

- Support for aptX LL. A modification of aptX technology, designed to minimize signal transmission delays. Encoding and decoding a signal when transmitting audio via Blueooth with aptX inevitably takes some time; This is not critical when listening to music, but in videos or games there may be a noticeable desynchronization between the image and sound. The aptX LL technology does not have this shortcoming; it also gives a delay, but this delay is so small that a person does not notice it.

- Support for aptX Adaptive. Further development of aptX; actually combines the capabilities of aptX HD and aptX Low Latency, but is not limited to this. One of the main features of this standard is the so-called adaptive bitrate: the codec automatically adjusts the actual data transfer rate based on the characteristics of the broadcast content (music, game audio, voice communications, etc.) and the congestion of the frequencies used. This, in particular, helps reduce energy consumption and increase communication reliability; and special algorithms allow you to broadcast sound quality comparable to aptX HD (24 bits/48 kHz), using much less transmitted data. And the minimum data transfer latency (at the aptX LL level) makes this codec excellent for games and movies.

– Support for aptX Lossless. The next branch of development of aptX technology, which allows you to transmit CD-quality sound over a wireless Bluetooth network without loss or use of compression. At the same time, audio broadcasting with sampling parameters of 16 bits / 44.1 kHz is carried out with a bitrate of about 1.4 Mbit/s - this is about three times faster than in the aptX Adaptive edition. Support for aptX Lossless began to be introduced in late 2021 as part of Qualcomm's Snapdragon Sound initiative, which is available on smartphones, headphones and speakers with a Snapdragon 8 Gen 1 processor and later.

— NFC chip. NFC is a technology for wireless communication over ultra-low distances, up to 10 cm. One of the most popular applications of this technology in smartphones is contactless payments, when the device actually plays the role of a credit card: just bring the device to a terminal that supports contactless technology like PayPass or PayWave. Another common way to use NFC is to automatically connect to another NFC-compatible device via Wi-Fi or Bluetooth: gadgets brought close to each other automatically set up a communication, and the customer only needs to confirm it. Other options are technically possible: recognizing smart cards and RFID tags, using the device as a travel card, access card, etc. However, such use formats are much less common.

- Infrared port. The infrared port looks like a small “eye”, usually on the top end of the phone. This equipment allows you to turn your phone into a remote control for controlling various equipment - just install the appropriate application. At the same time, we note that among such applications you can find an option for almost any device - from TVs to air conditioners, hoods, etc. Accordingly, the “smartphone remote control” turns out to be very universal.

— Walkie-talkie. Built-in radio module that allows you to use the phone as a walkie-talkie - for communication over relatively low distances without using SIM cards. Of course, for such communication you will need another walkie-talkie (or a phone with this function). The specific frequencies supported by the built-in radio module should be clarified separately; however, all phones with this feature operate in one or more standard bands. In practice, this means that they are capable of communicating not only with similar phones, but also with classic civilian walkie-talkies - provided they match the supported bands. The communication range is usually quite low; however, the built-in walkie-talkie can be very useful for tech in situations where conventional mobile communications are ineffective or unavailable. Typical examples of such situations are staying “far from civilization”, in an area of poor treatment, or traveling abroad, where roaming is expensive.

– Satellite communication. The satellite communication function is intended to send emergency alerts to rescue services in emergency situations. Smartphones with the ability to connect to satellite frequencies can communicate with emergency services in areas where there is no mobile network treatment. For better signal reception from satellites, it is advisable for the customer to be in an open space. At the stage of function formation, only ready-made requests can be transferred. In the future, it is planned to support full messaging via satellite communications, but a separate fee will be charged for them.

The capacity of the battery that the mobile phone is equipped with.

Theoretically, the high capacity of the battery allows the device to work longer on one charge. However, actual battery life time will also depend on the power consumption of the gadget — and it is determined by the hardware specs, the operating system, special solutions provided in the design, etc. So in fact, phones with capacious batteries in general have "long battery life”, however, the actual battery life can differ markedly even for two models with similar specifisations. Therefore, for an accurate assessment, it is better to focus not on the battery capacity, but on the operating time in different modes directly claimed by the manufacturer (see below).

The materials of which the bezel (side edging) and the back cover of the device are made.

In our catalog, this data are indicated in two words — frame material and cover material. For example, a device with a glass back and metal edging would be labeled as "metal/glass" (bezel first, then lid). Two words are specified even if the same material is used for both elements — for example, "metal/metal" for an all-metal case.

The main bezel materials include plastic, metal, glass, rubber, and ceramics. Back covers are also made mainly of plastic, metal, ceramics or rubber, and among glass there is a special variety — Gorilla glass parts. Occasionally, more specific materials are used, such as leather. Here is a more detailed description of each of these options:

— Plastic. A fairly simple, inexpensive and at the same time versatile and practical material. Actually, nowadays there are many varieties of plastic on the market, which differ in price and practical properties; so that the general property of this material depends primarily on the price category of the device. The easiest...way to give cover an unusual design is using plastic, although this design is also found in other materials. In general, all types of plastic in modern phones can be divided into glossy, matte, fluted and soft-touch. The gloss looks the shiniest, but dirt is very noticeable on it (first of all, fingerprints), moreover, such cases tend to slip in the hands. Matte surfaces are not as good-looking, but they are less sensitive to dirt. Soft touch is a special kind of matte plastic: due to the specific surface texture, this material is perceived as soft to the touch, similar to rubber. Also, it is perfectly held in the hands and almost does not slip. Fluted plastic is considered the most reliable in this regard — with signature notches on the surface; however, not everyone likes the look and feel of such surfaces when held.
As for combinations with other materials, plastic frames can be provided in metal and glass cases — for a secure hold; and plastic covers can be supplemented with metal or rubber frames for increased reliability.

— Metal. Usually metal most often means aluminium alloy. This material combines high strength, low weight and good thermal conductivity (the latter is especially important for removing heat from the hardware of performant smartphones). Metal cases are relatively rarely made in bright colours, but such a design is also possible; in addition, even without additional coloring, this material looks good. In general, it costs more than plastic, but nowadays even low cost phone models can be made of metal. At the same time, the metal frame can be combined with almost any cover material, however, such frames are especially popular in models with a glass back panel — the metal gives the case additional strength. Metal covers are found mainly among all-metal cases, less often in combination with a plastic frame (it allows you to reduce the cost and improve the permeability of the case for communication signals).

— Glass. Phone cases usually use special tempered glass of increased strength (a special kind of such glass — Gorilla Glass — is indicated separately, see below). Theoretically, glass is more sensitive to shock than most other materials, but in fact it is still quite difficult to break such a surface. At the same time, these cases look quite stylish and unusual. Their disadvantages include a rather high cost, as well as the signature features of glossy surfaces — the tendency to slip out of hands and "collect" dirt, especially fingerprints. In terms of specific body parts, glass is most often used for back covers; they are often complemented by frames made of more durable material (usually metal). But glass frames are usually part of all-glass cases — other design options do not make sense for a number of reasons.

— Gorilla Glass. A special type of high-strength glass from which back covers can be made. For glass in general, see above; and Gorilla Glass features are detailed in the Main Display section. We only note that, as in displays, different versions of such glass can be used in the rear panels of the case, differing in resistance to shock and scratches.

— Rubber. Usually, in this case we are talking about a body or a frame made of a hard material (plastic or metal) with an additional rubber coating. The use of such a coating is an unmistakable sign of a phone with a high degree of protection — waterproof, and often also shockproof. Rubber is the optimal material for such devices: it perfectly resists both moisture and shock, well insulates the hardware from cold and heat, while such a surface is pleasant to the touch and does not slip in the hand. The main drawback of this material is its bulkiness: the rubber coating must be quite thick, so that it noticeably affects the dimensions of the device. Thus, it makes sense to pay attention to this option in occasions where security is more important for you than compactness. At the same time, we note that the rubber case can be combined with a metal frame, and the rubber frame can be installed on a plastic device; these options also turn out to be quite reliable.

— Ceramics. Ceramics is material made by sintering raw materials at high temperatures. Mobile phones use special high-strength types of such materials. The advantages of ceramics include a stylish appearance and good reliability in most situations. On the other hand, such compositions are still quite sensitive to impacts (especially point impacts), they tend to slip in the hands, and they are not cheap. Therefore, ceramics is rarely used in modern mobile phones — mainly as a fashion material in fairly advanced models. Most of these models combine a ceramic lid with a metal frame; all-ceramic cases are noticeably less common.

— Leather. A rather rare and specific material, used mainly as a design solution. Leather covering in such cases is provided for the back cover, while the frame is made of metal or plastic. This material gives the device a solid appearance, emphasizing the status of the owner; in addition, it is pleasant to the touch and does not allow the device to slip out of the hand. However, leather is expensive and not reliable: it is easily scratched and torn even with light contact with sharp objects, and is also prone to abrasion. Therefore, such cases are not popular even among high-end phones.