Hothands Super Warmers are rectangular shaped single-use air-activated heat packs that are larger and last longer than standard heat packs. They provide up to 18 hours of continuous warmth for the hands and body. When to use Hothands Super Warmers? Hunting & Fishing Camping & Hiking Skiing Working in the yard Shopping Working Outside Hothands Super Warmers Features: Up to 18 hours of heat Super Warmer is Larger Size and Longer Lasting! Ready to Use Air-Activated Safe, Natural Heat Contains one warmer 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.