Our disposable hand warmers contain iron powder, activated carbon and super absorbent resin. It prevents oxygen from penetrating too quickly, releasing heat and burning, and does not penetrate oxygen too slowly, without temperature. Its use method is very simple: first, wash your hands with warm water to open the hand warmer package, put it on the hand naturally heating up, hands covered with the hand warmer, hands will slowly warm up, can be used for ten hours. And you can warm your hands.