Hothands Adhesive Body Warmer are single-use air-activated heat packs that provide up to 12 hours of continuous warmth for anywhere on your body. When to use Hothands Adhesive Body Warmer? Hunting & Fishing Camping & Hiking Skiing Working in the yard Shopping Working Outside Hothands Adhesive Body Warmer Features: Up to 12 hours of heat Ready to Use Air-Activated Safe, Natural Heat One per package Made in USA How do Hothands warmers work? Hothands contain ingredients like iron, activated carbon and water. Once these ingredients come into contact with the oxygen in the air, the ingredients oxidize and produce heat. The combination of ingredients has been specially formulated to ensure a constant and comforting heat for a wide variety of uses.