Simpson's Hybrid S model is currently the only Frontal Head Restraint proven effective for 3-point harnesses, and the device is also FIA and SFI approved. Additionally, in a partnership with Detroit auto manufacturers, the Hybrid S is third party tested to FMVSS208.

The Hybrid S allows high-performance driving Instructors, auto manufacturing test engineers, and other drivers with 3-point harnesses access to the advantages of head restraint safety.

The FIA Hybrid Head Restraint, in conjunction with a Snell or FIA rated helmet and a 3-point harness, reduced neck tension significantly when compared to a test with only a helmet and 3-point harness.