Most forward-facing seats can be used when a child is at least 1 year of age (some require 2 years), and 10 kgs. (22 lbs.). It is safer to leave a child in his rear-facing child seat until he outgrows it, then progress to forward facing. Forward-facing child seats must be used until the child has reached at least 18 kgs. (40 lbs.). Many forward-facing seats allow a child to use the internal harness well beyond 18 kgs (40lbs.); some as high as 29.5 kgs (65 lbs.). It is safer to leave a child in his forward-facing seat until he is either too tall or too heavy for it.