Ergodyne Chill-Its 6200S Phase Change Cooling Vest, Small/Medium, Khaki Size Small Medium fits chest size 32 to 40 inches Adjusts at the shoulders and around the body for a comfortable fit Cotton Banox FR3 Fabric passes ASTM F1506; ATPV of 9.4 cal/cm (HRC 2) Maintains constant 55 degrees to keep workers cooler, safer and more productive for up to two hours. Phase Change Packs recharge quickly in freezer, ice water or refrigerator