Child safety 035 Children Seat Class 2 child seat Child Seat Classification (for reference only) : 1 Class 0/0+ child seat For infants or toddlers under the age of 4 who weigh between 9-18 kg, a class 1 child seat with a seat belt is best. For children under the age of 7 weighing between 15-25 kg, it is best to use a three- point seat belt with a class 1 child seat. For restraining an infant under 9 months and 10 kg, as well as under 18 months and 13kg, it is better to use the 0/0+ child restraint seat which can be adjusted to the lie-down position. eat