Forty-seven out of 54 booster seats introduced last year have earned the Insurance Institute for Highway Safety’s (IIHS) highest rating, the organization has announced.

Booster seats are designed for children who have outgrown harness-equipped restraints. The IIHS said children aged four to eight-year-olds are 45 percent less likely to sustain injuries in crashes if they are in boosters than if they are using seat belts alone.

In its latest booster ratings program, the IIHS looked at the newest seats and awarded BEST BET, the top rating, to 47 boosters which it said provided a good seat belt fit for a typical four- to eight-year-old in almost any car, minivan or SUV.

“Booster seats are simple, low-tech devices that don’t have to cost a lot to be effective,” said Jessica Jermakian, IIHS vice president of vehicle research.

“All a booster needs to do is raise the child up a bit and guide the seat belt so it is positioned correctly. The lap belt should lie flat on the upper thighs and not up against the tummy, and the shoulder belt should fit snugly across the middle of the shoulder.”

IIHS has been rating boosters since 2008 on their ability to provide good lap and shoulder belt fit. its booster rating program after finding that many seats didn’t consistently provide good belt fit. In the Institute’s first booster ratings, only a quarter of the seats evaluated earned the BEST BET designation. Now, the vast majority of boosters tested meet that high standard.

Ratings for the new booster seats can be found on the IIHS website.

A list of ratings for all booster seats is also available online.