Phase change cooling technology pulls heat from the body via rechargeable cooling packs filled with non-toxic phase change liquids that, when activated/solidified, will maintain a temperature between 55° F (13° C) and 64° F (18° C). Depending on what you have available (cooler, fridge or freezer), activation takes between 5-60 minutes and lasts up to four hours. Because the charge packs do not require airflow to work, they’re an ideal choice for high-heat indoor settings like foundries, glass manufacturing and paper & pulp.