A car seat foot prop is a rigid leg that extends from a car seat base or the back of a convertible car seat to the floor of the vehicle. The purpose of a foot prop is to reduce the downward rotation of a rear-facing car seat in a crash. The force of rotation can increase the chance of injuries, especially to the head and spine. The use of a foot prop on rear-facing car seats can help reduce those injuries.

Foot props are not common on U.S. car seats at this time. In fact, only a couple of car seats have them. The Cybex Aton 2 and the Nuna Pipa infant car seats both have foot props and are available in the U.S. now.

One reason foot props are not common on U.S. car seats is because of the crash testing methods used in this country. Car seats are tested on specialized sleds that do not have the same type of floor as a passenger vehicle. That means it's difficult to test how the foot prop would work in an actual vehicle using the current test methods.

A foot prop usually has some method of adjustment for length and angle to fit a wide variety of vehicles. There's also usually a way to fold the foot prop in for storage. Some foot props have an indicator that shows you when it's being used correctly.