The R4 is a lightweight, form-fitting race collar offering protection against neck and collarbone injuries. The low-profile design makes it a comfortable, yet protective, piece of gear you can wear on the track or on the trail. Hard-molded upper surface disperses energy to the PU core. Hi-tensile, closed-cell PU core absorbs impact energy. BIOFOAM liner provides extra impact absorption. Rapid lock closure system for easy front entry. Adjustable rear strut for a customized fit.