Now You Can Have The Best Of Both Worlds In A Single Product. This Gel Pack Will Freeze Within 2 Hours, Or Heat Up In The Microwave In About 2 Minutes, And Will Maintain Either Heat Or Cold For Hours. The Pack Is Great For Use In Many Emergency First Aid Siturations. Can Be Used Over And Over. Easy To Use Best If Used With Cloth/ Not Against Bare Skin Keep One In The Freezer, And Another Available To Microwave Pack size : 5" X 6.5", Weighs 0.75 LB