Gel ice Thermo-strips are composed of corn starch & water. They are completely non-toxic and non-flammable. Thermo-strips will freeze overnight in a regular home style freezer. Documented to lower body core temperature. Cooling duration is dependent on environmental factors such as ambient temperature & humidity, but is typically 2-4 hours. Packs are segmented for maximum comfort and mobility. Each 15 ounce Thermo-strip measures 14″ L x 5″ W x .5″ H. For use with all Steele Cooling Vests except the Cool-UnderVest.