Speaker diameter
The diameter of the speaker installed in the device. In this case, we can talk about both the actual speaker installed in the speakerphone, and the headphone emitter that the Bluetooth headset is equipped with (see "Device"). Accordingly, the meaning of this spec in both cases will be different.
In general, the large size of the speaker, on the one hand, allows you to achieve better volume and more reliable transmission of low frequencies; on the other hand, it requires more space for installation. This is especially true for headsets, since the types of headphones used in them (see "Design") have severe size restrictions: earbuds are made no larger than 15 mm, in-ear solutions have a diameter of less than 10 mm (only the headphones of the same type may be compared by size with each other). Note that an earpiece that is too large may be uncomfortable, or even not fit in the ear at all. So the perfect option is to try on the headset before buying.
In turn, speakerphones usually use speakers with a diameter of about 50 mm — this size is considered the best compromise between overall efficiency and compactness.
Power source
The type of power used by the device. This parameter is indicated only for models with an independent power source: these are absolutely all Bluetooth headsets (see "Device"), as well as most speakerphones and some car kits (the last two varieties can also be powered from an external source — for example, from the on-board network of a vehicle or USB port).
Almost all self-powered devices run on built-in batteries, often non-removable ones. Such batteries can be made small and at the same time capacious, and their shape can be different — this makes it easy to integrate such a power source even into a miniature headset, not to mention larger accessories.
Replaceable silicone tips
Replaceable silicone tips that come in a box with with the Bluetooth headset (see "Device").
Modern headsets are traditionally equipped with in-ear headphones or earbuds (see "Design"); both of them are held in the ear by a soft attachment, usually made of silicone. The size of such a tip may not be suitable for the user — in this case, the ability to change it to another, more convenient one, will be essential. Most often, there are three replaceable tip in the kit — large, regular and small.
