Providing up to 10 hours of 130-140 heat, HeatMax HotHands warmers are a safe and easy-to-use heat pack that help keep your hands warm when the temperature gets cold. Air-activated heat packs are formulated to deliver a constant, comforting heat. Ultra-thin, rectangular pack fits into shoes, gloves, and other spots needing a shot of warmth easily. Safe and easy-to-use Air-activated Up to 10 hours of constant, comforting heat Ultra-thin rectangular packs fit easily in a variety of spots