TechNiche Heat Pax Air Activated Body Warmer is designed to provide heat and protect against cold temperatures. It is an easy-to-use heat pack that measures 3.5 x 5 in. which is ideal for Heat Pax powered items such as vests, neckwear, vests, back wraps, cushions, and blankets. It delivers more than 24 hours of safe, constant heat to keep your body from freezing. The heating can be paused by resealing in an airtight canister. This product is non-toxic and biodegradable; it does not use batteries, flames or chemicals to activate.