Chill-Its 6220 S/M Clear Phase Change Cooling Vest Charge PacksErgodyne Ei 12201 The Chill Its 6220 Phase Change Cooling Vest Charge Packs keeps workers cooler, safer and more productive. This charge pack is compatible with the 6215, 6225, 6230 6235 cooling vests. The phase change cooling material maintains a 64 F (18 C) temperature for up to 4 hours when activated. HOW TO USE *** Phase Change Vests not included. *** There are many ways to activate your cooling vest. Simply place the two removable packs in a