The Relief-Pak® Cold n' Hot® Compress has a comfortable soft fabric that conforms to the curves of your skin. Fabric is gentle on the skin, frost-free, and washable. Put the pack in the microwave or chill in the freezer. When heated, soothes discomfort from stiff neck, backache, arthritis, sprains and bruises. When chilled, soothes discomfort from injury, sprains and strains, muscle soreness, bruises, swelling and tension headaches. The non-toxic, non-crystallizing gel allows the pack to contour and stay pliable when heated or chilled. The pack can be used with a standard Velcro hook to hold the pack in place.