Features: improved ventilationskin friendly fabric coverprovides uniform and soft support.ultimate comfort.partial immobilization.heavy density soft polyurethane foam provides uniform, soft support.excellent aesthetics.improved ventilation provides more patient comfort and better compliance.skin friendly pv fabric cover provides patient comfort, allergy free use even to sensitive skineasy application and removal. Sizing details : measure distance between edge of sternum and lower jaw with neck.Size inches cmssmall 3 3.5 7.5 8.75medium 3.5 4 8.75 10large 4 4.5 10 11.5