This 3.875" circle handwarmer is designed so you can use it over and over again - saving the planet while keeping warm. This hot little item is a crystallization type handwarmer that activates by flexing the small disc inside to produce heat. It stays warm for about 15 - 25 minutes giving you that little extra warmth to get out there. To reuse, submerge in a pot of water and boil on stove for at least 15 minutes. Comes with storage pouch and can be used up to 300 times.