Our 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.