Yaktrax Hand Warmers are a safe easy and allnatural solution to cold hands Once opened and exposed to oxygen in the air these disposable but environmentallyfriendly 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 outdoorsHOW IT WORKSWhen 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