Replacement cooling packs are deployed to provide several hours of cooling relief to reduce fatigue and heat stress. For use with 390-EZHYPC EZ-Cool® Max combination phase change & evaporative cooling vest.• Cooling packs are deployed in a variety of shapes and sizes for personal comfort and maximum cooling results• Protection from stress of high temperatures outdoors and indoors• Includes 1 set of 4 cooling pack inserts• Cooling effects last for up to 3 hours• To activate place in freezer, refrigerator, or cooler with ice set at 58ºF• Set time of 45 minutes to ensure packs are frozen solid throughout• PCM is non-flammable, non-toxic, and non-combustible