The Heat Factory Mini Warmer is a soft, light-weight pouch containing an inert mixture of iron powder, charcoal, salt, water and vermiculite. When exposed to air, a natural exothermic reaction generates consistent and prolonged heat. The pouch is made of soft cloth lined with a very thin layer of porous plastic for maximum durability. The warmers are odorless, non-toxic and air-activated. Soft, lightweight pouches are specially engineered to provide heat that's long-lasting, comfortable, and even. Keep handy in luggage, car, or gear bags for anytime use. Includes 12 pair (24 total) heat packs that last 10+ hours.