What are the weight and height limits for rear-facing use?

The rear-facing weight limit is 1.8–18 kg (4–40 lbs) and the height limit is 43–102 cm (17–40 in.). Additionally, the top of the child's head must be at least 2.5 cm (1 in.) or more below the top of the child restraint headrest. Once your child exceeds any of these requirements, they must transition to forward-facing orientation if possible. (Page 4)