The Britax Evolva 123 is suitable for use from 9 to 36kg, the Evolva has 2 belt adjustments to allow the car seat to grow with them. From 9 – 18 kg your child is secured with the seats Click & Safe audible harness system. Then from 15- 36kg the harness is removed and the child is secured with the cars 3 point belt, seatbelt guides will ensure that you position the belt correctly across your child. To keep your child comfortable there is an upright and recline position, the headrest, side wings and harness can be adjusted to the appropriate height. Evolva 1 2 3 has deep padded side wings for Side impact protection.