Child car seat series britax rmer evolva 1 2 3 plus carry weight 9 36 kg age 9 months 12 years group 123 side impact protection harness system 5 point safety harness padded seat belt padded clasp exterior measurements 52 x 60 x 47 weight 8 kg adjustable backrest central belt adjustment height adjustable adjustable headrest 7 x colours grey black slip cover washable cover