Hand Warmers, Hand Warmer Portable Comfortable Self-Heating Warm Patch Belly Warm Patch Belly Warm PatchOur Hand Warmers contains iron powder, salt, activated carbon. It can release heat through a chemical reaction, raise body temperature, and warm hands to relieve local pain. Its use method is very simple: after opening the package, take out the patch and stick on the inside of the clothes, the patch will start to heat in 15 30 minutes, and the insulation effect can last for 10 hours. The heat can last up to 10 hours to warm your hands, body and feet.