No IIHS rating for the Mifold belt-positioning device

The BubbleBum inflatable booster referred to below was removed from the BEST BET list in February 2022. Read more.

Although booster seats are easy to use, caregivers sometimes wish they could be more portable. Lugging one on vacation or around town in case of a taxi ride can be difficult. A few products such as the BubbleBum inflatable booster, which earns a BEST BET from IIHS, have tried to address this issue in recent years.

A new device called the Mifold Grab-and-Go Booster is the latest attempt to solve the problem. It folds up neatly and is small enough to carry in a handbag. However, the Mifold isn't really a booster, despite its name. It is more accurately described as a belt-positioning device.

IIHS rates boosters for their ability to correctly position a vehicle safety belt on a child. However, they have two other important characteristics that are separate from belt fit.

One is that they boost the child up, which changes the angle at which the lap belt holds the child. Among boosters rated by IIHS, the average highback seat raises the child nearly 5 inches, and the average backless booster raises the child 3½ inches.

The other characteristic is that they effectively shorten the seat cushion depth, which allows children to bend their legs comfortably over the edge, making them less likely to slouch. This keeps them in a good position in the event of a crash.

The Mifold has a thin cushion that raises the child only about three-quarters of an inch and doesn't affect the depth of the seat cushion. Instead, the device pulls the belt down to the child. There aren't any data about how this new type of device works with real kids in real crashes. For these reasons, the Mifold isn't comparable to the boosters that IIHS evaluates and isn't included in the ratings.