Flex-i-Cold stays flexible up to -4 degrees Fahrenheit and will conform to the body. This non-toxic gel is encased in a puncture-resistant bag for multiple uses. You can heat this pack in the microwave or boiling water for use as a heat pack. Always follow label instructions for safe use.Packs remain flexible out of the freezer for an extended period of time. Non-toxic and non-caustic, bio-degradable – simply keep in freezer until needed. Available in 2 sizes, and sold in cases of 12.