(NBC NEWS) -- A car crash is violent enough to a child, even when the child is properly restrained. But they can be fatal if the child is not.
Now, new testing by the Insurance Institute for Highway Safety concludes at least manufacturers are making better booster seats.
"So, this year there are 31 new booster seats on the market. 19 of those are in the institute's top rating of best bet" says Jessica Jermakian of the Insurance Institute for Highway Safety.
Seats like the Parkway SG, in highback mode, made by Britax and
the Transit Deluxe made by Harmony both received top ratings because the lap belts lie flat across the upper thigh.
The shoulder belt also fits snugly across the center of the shoulder.
"It's not sliding off the shoulder or riding up on the neck." explains Jermakian.
Two boosters seats,both from Dorel Juvenile Group, ended up on the institute's "not recommended" list.
Although Dorel says both "....are in compliance with and exceed all federal requirements for child restraint systems."
Boosters have proven effective at protecting children during a crash. But experts say there's no need to rush your child into one.
"The institute recommends that parents keep their children in a harness-based restraint for as long as possible up to the height and weight limit of the seat" says Jermakian.
That generally means somewhere between ages 4 and 8.