The Chill-Its 6215 Premium Phase Change Cooling Vest with Packs helps to keep workers cooler, safer and more productive, maintaining a 64°F (18°C) temperature for up to four hours when activated. The vest is made of a modacrylic cotton blend flame-resistant fabric, which meets ASTMF1506 requirements as well as being classified to NFPA (CAT1). The adjustable hook-and-loop closures at the shoulders and waist provide a customized and comfortable fit. There are many ways to activate your cooling vest. Simply place the two removable packs in a cooler of ice water for 10 minutes; freezer for 15 minutes; refrigerator for 25 minutes; or near an air conditioner for one to two hours. Then place the recharged cooling packs in the vest pockets for hours of cooling.