Side protection (or side impact protection) varies my manufacturer and child car seat design. It can be already integrated into the seat or even added on as an extra. Side protection that does require adding or adjusting is used on the side of the child restraint closest to the vehicle door. If the seat was positioned in the centre of the vehicle it would not be required.
Side protection overall forms part of the restraints shell. It helps reduce forces by absorbing energy and forces at the sides prior to it reaching the child in the seat.
The picture above is a Britax Kidfix highback booster. Although the restraint has deep side protection as part of the shell. It also features adjustable side protection (the two black circles). Depending on what side of the vehicle the restraint is fitted, you can add an extra layer of protection with the side impact adjuster. Britax calls this SICT. Side Impact Cushion Technology.
Child restraint manufacturers use various amounts of terminology when describing side protection or side impact protection. The seat above is also a Britax restraint. On the seat, it describes ‘SICT inside’. As above the SICT is Side Impact Cushion Technology ……but inside. All the side protection is built-in within the shell of the restraint. No manual adjustments are required.