Yaktrax© Hand Warmers are a safe, easy, and all-natural solution to cold hands. Once opened and exposed to oxygen in the air, these disposable but environmentally-friendly warmers begin working in just minutes. Slip them into a pair of gloves or jacket pockets and create a cozy cocoon for your hands that lasts up to 8 hours. Yaktrax Warmers are the ideal choice for outdoorsman, winter athletes, spectators, and anyone who works or plays outdoors. HOW IT WORKS When exposed to oxygen in the air, the iron filings inside the pouch begin to oxidize creating a rapid rusting process which in turn produces residual heat. Salt acts as a catalyst, while carbon helps to evenly disperse the heat. Vermiculite acts as an insulator that helps prevent the heat from dissipating too quickly. 2 WARMERS PER PACK UP TO 8 HOURS OF HEAT SAFE, NATURAL HEAT ENVIRONMENTALLY FRIENDLY AIR-ACTIVATED ODORLESS