The Chill-Its Lightweight Phase Change Cooling Vest Packs are made to be inserted into model 6255 Lightweight Phase Change Cooling Vest (sold separately) to keep workers cooler, safer and more productive. The phase change cooling material in the packs is 100% biodegradable and maintain a 64° F (18° C) temperature for up to two hours when activated. These packs are designed to be 30% to 60% lighter weight than other cooling vests on the market. Simply place the two removable packs in a cooler of ice water for five minutes; freezer for eight minutes; refrigerator for 12 minutes; or near an air conditioner for one hour. Then place the recharged cooling packs in the vest pockets for hours of cooling. The cooling pack should be washed by hand with a mild detergent and warm water. Do not machine wash or machine dry. This body cooling vest is perfect for anyone in need of instant cooling relief while working or playing outside or indoors in warm temperatures.