Car Seats

Once your child weighs at least 40 pounds and his ears have reached the top of his car seat, he is ready for one of the types of booster seats described below:

• Belt-positioning booster seats use lap/shoulder belts, which raise your child so the lap and shoulder belts fit properly. This helps protect your child's upper body and head. Both high-back and backless models are available.

• Shield booster seats are designed to be used with lap belts. However, this type does not provide enough upper-body protection, so only use it when lap/shoulder belts are not available. More importantly, this type of booster seat is not approved for children who don't weigh as much as 40 pounds because they may be thrown (ejected) from the booster seat if there is a rollover crash.  Do not attach belt-positioning devices to a booster seat. Shield boosters should only be used without their shields because such devices may pull the lap belt up onto the child's stomach, causing severe injuries in a crash. There also are no federal safety standards for such devices, so the National Highway Transportation Safety Administration does not recommend their use.

• Combination seats are seats that can be used first as forward-facing car seats (for children who weigh at least 20 pounds and are at least one year old) and later, as booster seats.

Your child should use a booster seat until the car's seat belt fits properly, which is usually not until he or she is at least eight years old or over 4 feet 9 inches tall.