Our disposable hand warmers contain vermiculite and activated carbon. It can keep us warm in the cold winter. It won't let the oxygen penetrate too fast, lose heat and burn. Its use method is very simple: 1. After opening the package, take out the patch and stick it on the inside of the clothes. 2. The patch will start to heat up in 15-30 minutes. 3. The insulation effect can last for 10 hours. And can be applied to the skin naturally long-lasting heat, no need to shake or knead warm hands/antifreeze.