Our disposable hand warmers contain vermiculite and activated carbon. They can keep us warm in the cold winter without letting oxygen penetrate too quickly or burning away heat. They are easy to use: 1. Open the package, take out the patch and stick it on the inside of clothes. 2. The patch will start heating within 15-30 minutes. 3. The insulation effect can last for 10 hours and provides long-lasting warmth without shaking or kneading