Heat Factory Warmers are soft, lightweight pouches which begin to activate and generate their own heat when exposed to the air. They can be used any time you need instant continuous warmth anytime...anywhere. Adhesive Toe Warmers last up to 5 hours. Heat Factory's Toe Warmers are designed to work in a shoe or boot with restricted air flow. Simply open package, peel off backing and place on the outside of socks under the toes, each package contains two warmers.