They Are designed to prevent drivers and passengers from being completely ejected from a vehicle by spreading out their bodies’ energy over their shoulders, chest, and pelvis rein a collision. For the reasons discussed above, NHTSA is denying Cybex's request to provide guidance on how FMVSS No. 213a's test procedures https://vuf.minagricultura.gov.co/Lists/Informacin%20Servicios%20Web/DispForm.aspx?ID=10574680