Thaw disposable foot warmers are full-sole, insole-shaped heat packs that warm the whole underside of the foot. They are air-activated, so they start heating soon after the packet is opened, with no batteries or fuel, and give 7 or more hours of heat (maker's figure). An adhesive backing keeps them in place on the sock inside your boot or shoe. They are odourless, ready to use, TSA approved for air travel and have a shelf life of about three years unopened. Each warmer is single-use. Good for hunting, fishing, winter sport, outdoor work or a cold stadium. This bulk box holds 30 pairs.