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 Features: Hard molded upper surface disperses energy to PU core Hi-tensile closed cell PU core absorbs impact energy Bio-foam liner provides extra impact absorption Rapid lock closure system for easy front entry Adjustable rear strut for a customized fit