Booster car seats are to be used only for toddlers in a forward facing position. The minimum weight requirement varies from 30-40 pounds, depending on the model you select. The good news is that the booster car seat can take your child safely to 80 pounds in a car seat. As infant car seat laws change and vary state to state many states are going with higher weight requirements for children in car seats.
This type of car seat can have its own set of buckles or harness or it can use the seat belt already found in your car. Your child's height will dictate which is most comfortable. So I'd recommend trying the car seat out with your child prior to purchasing it.
Photo © Robin Elise Weiss
