Engel 5°F / -15°C Freezer PacksEngel Ice changes phase at 5F, efficiently keeping frozen food and drinks frozen. The active ingredients are non toxic and housed in a rugged container designed to provide maximum surface area to increase the efficiency at which they cool. Engel Freezer Packs will maintain freezing temperatures for hours or even days. When finished using, simply recharge in your household freezer until needed again. Freezing takes about 6 8 hours. It is recommended to