It must fit your car properly. The best way is to bring your car to the store and test-fit the seat. It must be reasonably easy to install and remove. To make installation easier, newer child seats are equipped with LATCH or Isofix attachments. These are buckles or straps that attach to mounting points in the car without the need for a seat belt. Newer cars (all new cars sold in the U.S. from 2000 onwards, for example) have LATCH/Isofix mounting points in the rear seating area. It’s a good idea to consider this feature when buying a car.
It must have passed safety standards as mandated by American or European law. Look for indications that a child seat has passed such regulations, usually stamped on the box, indicated in the manual, or labeled on the seat itself.
Buy a seat appropriate for your child’s size and weight.
Choosing a booster seat
Look for the “horns” on the booster seat bottom. The pelvic bones of a child have not developed the distinctive structure called the iliac crest, necessary to keep the belt from riding upward in an accident. The horns on the booster perform this function.
Comfort is also a factor. It will be more difficult to keep a child in the seat if he is not comfortable. Keep the child snug but not tightly constricted.
Booster seats with “wing” projections at the head area help keep the child’s head upright if he falls asleep.