An infant car seat can only be used in a rear-facing position, with a typical height limit between 40 - 83 cm/15 - 33 in, a maximum weight of 13 kg/29 lbs, and for babies until approximately 15 months of age. The Bugaboo Turtle Air by Nuna belongs to the infant car seat category. A convertible car seat can be used in a rear-facing position as well as a forward-facing position depending on the child's height and weight. This is typically between 40 - 105 cm/15 - 41 in, a maximum weight of 18 kg/40 lbs, and until approximately 4 years old. The Bugaboo Owl by Nuna belongs to the convertible car seat category.