Our Foot Warming Pads contain iron powder and activated carbon. They generate heat to provide sufficient warmth for the soles of your feet or body; they are very helpful for women with menstrual cramps, back pain, and cold hands and feet. Using them is simple: peel off the non-woven fabric sticker; stick the patch on the outside, put on socks, and enjoy warmth for 6-8 hours. They are convenient to use and can be used for outdoor activities, providing warmth in cold seasons