Comparison Britax Romer KidFix III M vs Britax Romer Duo Plus

The weight of the child for which the car seat is designed.

In total, there are 5 main weight groups: 0 (0 – 10 kg; a rather rare option nowadays), 0+ (0 – 13 kg), 1 (9 – 18 kg), 2 (15 – 25 kg), 3 (22 – 36 kg). However, many car seats are produced that belong to several groups at once: 0 +/1 (0 – 18 kg), 1/2 (9 – 25 kg), 2/3 (15 – 36 kg), 0 + / 1/2 (0 – 25 kg) and even 1/2/3 (9 – 36 kg) and 0+/1/2/3 (0 – 36 kg). Such versatility affects the price, sometimes quite noticeably. On the other hand, a seat that matches several groups at once remains relevant for a child longer, and it usually costs less than two (or even more) separate products, each for a different weight category.

Note also that the weight group is directly related to age; refer to "Age range" for details.

The age of the child for which the car seat is designed. Many models combine several age groups at once; such products, naturally, cost more, but remain relevant for the baby longer.

Note that this indicator is directly related to the weight group; Here are the main age ranges that are found nowadays, and the weight categories to which they correspond:

— 1 – 6 months (weight group 0); rare today.
— 1 – 12 months (weight group 0+); almost completely replaced the category "0".
— 8 – 48 months (weight group 1).
— 3 – 7 years (weight group 2).
— 6 – 12 years (weight group 3). Note that if only this weight category is indicated for the car seat, then it is a booster: a lining without a backrest, which is placed on the standard car seat and allows the grown-up child to use "adult" seat belts. If the note "6 — 12 years" is combined with another weight category - then we have a full-fledged car seat with a backrest.

In conclusion, it is worth saying that this characteristic is not strictly defined: children of the same age may differ in development and build. So, when choosing a seat, first of all, weight should be taken into account, and then age; and if the seat corresponds to the child's height and build, there is nothing wrong with the age discrepancy.

Recommended values of the minimum and maximum height of the child (in centimeters), at which the car seat provides optimal safety and comfort. The parameter must be taken into account when choosing a child car seat along with the age and weight groups, because children of the same age can have different heights and weights.

— Backrest tilt adjustment. The backrest tilt can be adjusted. This point is different for various weight groups. In groups 0+ and 1 not the backrest, but the whole seat tilts against the fixed base, and in groups 2 and 2/3 only the backrest tilts. The possibility of adjusting the backrest tilt is important if the child is in the car for a long time – by tilting the backrest you can let the child sleep or rest.

— Headrest height adjustment. According to safety requirements, the child's head should not be more than one third above the headrest, so it is necessary to adjust the headrest as the child grows.

— Harness height adjustment. The ability to adjust the height of car seat harnesses — such a need arises as the child grows.

— Backrest width adjustment. The ability to adjust the width of the backrest allows you to optimally adjust the car seat not only for constantly changing height, but also for the child's complexion.

— Horizontal position of a backrest. The backrest of the car seat is horizontal. The horizontal position is optimal for babies under the age of six months, since it avoids unnecessary stress on the spine, therefore group 0 car seats usually have this function.

— Removable backrest. It is possible to comp...letely remove the backrest of the car seat. This function expands the possibilities of the seat: it can be used both for its intended purpose, with a backrest, and as a booster (for more information on boosters, refer to "Weight group 3").

— Swivel system. The seat swivels relative to a fixed base. This makes it easier to drop off and pick up the child: during these operations, the seat can be turned to face the car door, and when driving, it can be positioned in or against the direction of travel.

— Isofix base. The product is equipped with a separate Isofix base, which is fixed in the interior of the car on the appropriate fixing clips, and the car seat is installed directly on it. The use of the base provides reliable fixation of the car seat and reduces the risk of its incorrect installation. On the Isofix base are installed mainly car seats of age groups 0+ and 1, some models assume the possibility of placing seats for older kids. It should be noted that car seat models without an Isofix base are also widely available on the market. — Removable cover. Removable car seat cover for cleaning and/or washing. This function is especially useful if the seat is used when feeding a kid.

— Anatomical cushion. Depending on the age group, it can either be a special horseshoe-shaped cushion to support the kid's head (for the youngest ones who are still unable to hold their head on their own), or a special soft headrest that fixes the head from behind and to the sides (for older kids).

— Armrests. Armrests refer to the handles placed on the sides of a seat where one can rest their elbows and forearms. They reduce fatigue in the neck and shoulders of a child during prolonged sitting.

— Sun canopy. Plastic (most often) canopy to protect the kid fro...m the sun or bright light.

— Foot cover. A cover that covers the kid's legs and lower body. It is used in seats of age group 0.

— Cup holder. A device used in car seats to hold a bottle of drink or formula for feeding. Most often done removable.

The car seat has structural elements that further protect the child from side impacts. At least such elements include sidewalls for head protection made of impact-absorbing material such as polyurethane foam; torso protection may also be provided. If you are looking for a car seat with the maximum level of protection, you should choose from models with additional side protection.

The type of harnesses installed in the car seat. The most popular models are 5-point, which can cover absolutely any age category. 3-points are more common in models for newborns. And the bumper is not at all connected with the belts, but it also reliably protects the kid. At the same time, there are also 2-point and 6-point (exclusive rare options for the carrycot) and car seats without belts. More details about each of them:

— 2-point. A harness that covers the child's body around the waist. A rather specific option, found in two types — baby carrycots (refer to "Weight group") and boosters, in which the main fixation is provided by the vehicle's seat belt.

— 3-point. Three harnesses (two across the shoulders, one between the child's legs) that converge in a buckle located near the abdomen.

— 5-point. In addition to the shoulder and crotch harnesses (as in 3-point), they have two additional harnesses at the waist. Such a system is more expensive, but more reliable than a 3-point system.

— 6-point. A distinct format, positioned as a safer alternative to 5-point harnesses, involves harnesses crossing over the shoulders, attaching to special stops on the chair, wrapping around the hips, and securing in a clasp between the child's legs. This configuration aims to minimize the risk of abdominal and ge...nital injuries during a collision by keeping the clasp in the seat. However, due to the increased complexity of setup and use compared to 5-point harnesses, this design is less common.

— Bumper. The bumper, distinct from a harness, is a specialized rigid device covered with soft material for the child's comfort. It securely encases the child's torso, from chest to crotch, leaving the head, arms, and legs free without requiring additional harness straps. This design offers the advantage of distributing impact load evenly across a wide surface area in the event of an accident, unlike narrow harnesses. Some models even feature the bumper as a usable game table. However, drawbacks include weak upper torso fixation and potential discomfort for the child in warm weather.

— None. The complete absence of own harnesses in the design of the car seat. This feature is found in models of older age categories, where it is supposed to fasten the child with a standard car seat harness.