As first-aid to alleviate heat-caused stress or the pain of minor injuries, the Disposable Instant Cold Pack helps bring immediate - but short-term - relief from heat stress, bruises, sprains, cuts, burns, etc. Commonly inside the packet are two ingredients: water (in a breakable container) and either ammonium nitrate, ammonium chloride, or urea (in crystal form) . Squeezing the packet to release the water causes an endothermic reaction that results in a significantly lower temperature for a period of about 15-20 minutes. Available from outlets (retail store or online) that carry medical supplies and under many brand names (e.g., Medride, Dynarex. COOL, Therma-Kool, BioFreeze, General Medi, AffordTex, ACE).