The Heat Factory Mini Warmer is a Heat Factory innovation that revolutionized the U.S. warmer industry over 20 years ago. These lightweight pouches contain a mixture of ingredients that, when exposed to air, create an oxidation process generating heat. The Mini Warmers are our most popular size warmers and last 10 hours. They can be used in gloves, pockets, Heat Factory Headwear, and any place where soothing heat is desired. Mini Warmers are sold as pairs ONLY.