Little Hotties Hand Warmers are all-natural, disposable hand, body, and toe warmers. LITTLE HOTTIES WARMERS are used by athletes, sportsmen, skiers, construction workers and anyone wanting to stay warm during outdoor activities. When exposed to oxygen, the iron in the pouch oxidizes and produces heat. When iron oxidizes, it produces iron oxide - more commonly known as rust. The salt acts as a catalyst, while the carbon helps disperse the heat. The vermiculite is used as an insulator for the purpose of retaining heat. All of these ingredients are enclosed in a polypropylene bag. Polypropylene allows air to permeate the ingredients while holding in moisture.