The R4 model has a multi-layer construction that distributes the load so that it keeps individual ribs from moving independently. At the same time, the R4 does not dig into the driver at the edges and does not create additional pressure points due to its comfortable soft inner sponge layers.

The R4 was developed to protect the 3/4 and lower backs from rib injuries. It is very lightweight and is also the thinnest hard shell rib protection available. The R4 has an adjustable back angle to match many different chest angle shapes and it has an elastic Velcro attachment for added comfort and convenience.