Our hand warmer contains sodium chloride and vermiculite. It releases heat, raises body temperature, and warms hands. Its use method is very simple: 1. After opening the package, take out the patch and stick it inside the clothes. 2. The patch will start to heat up in 15-30 minutes. 3. The insulation effect can last for 10 hours. It can also be used for winter activities, including outdoor outings, writing for warm hands, and topical pain relief.