You slam the brakes to avoid rear-ending the car that just cut in front of you and whip around to check on the baby. The little one is still fast asleep in her rear-facing car seat, oblivious to the whiplash effect that hit everyone else. The law in all 50 states requires car seats, but it is not enough just to have a car seat; it also has to be the right type and size for your child. Newborn car seats are rear facing, while toddler and child seats are forward facing. Older children need booster car seats in every state except Florida and South Dakota. These seats raise the child to the correct height so the seat belt crosses at the chest level instead of at the neck. Studies show that age-appropriate car seats are safer and more effective than convertible seats that "grow with the child." While it can be expensive to change car seats at the recommended times, eBay's huge selection makes it simple and affordable to find the right seat at the right price.