Unlike other heat packs, Clix works with NO electricity, and NO microwave. They instantly warm up to 130*F/54*C with just a click of a button! You can use the flexible Clix pack on any part of your body. This is a cutting-edge solution that’s 100% non-toxic, safe, and reusable! To use as a cold pack, simply place in the refrigerator until you get your desired temperature.