Cura-Heat Back & Shoulder are specially designed rectangular heat packs to help provide 12-hour warming relief from minor joint aches and pains. It helps to deliver heat therapy in an easy to use format and works by increasing blood flow to the source of pain to decrease stiffness and relax sore muscles. Unique design The patches are convenient to use, and can be worn on under clothing, as they are designed with a thin, discreet design. They are portable enough to be carried anywhere. This product is fragrance-free and non-medicinal. How it works Cura-Heat Period Pain contains the ingredients such as iron, activated carbon and water, which oxidise and produce heat when it comes into contact with the oxygen in the air, to provide constant, comforting heat.