Up to 10 hours of heat. Ready to use. Air activated. Safe, natural heat. Hothands, the leader in air-activated warmers, has been warming hands, feet, and bodies for over 20 years. It's a brand trusted all over the world by professional athletes, outdoor sporting enthusiasts, spectators, skiers, outdoor workers and by anyone wanting safe, convenient, concentrated warmth in cold weather conditions. Average Temperature: 135 degrees F (57 degrees C). Actual duration depends on usage and storage conditions. Share your feedback at: feedback.HotHands.com for a chance to win an assortment of Kobayashi products. Consumer comments call: 1-800-432-8629. HotHands.com. Made in the USA using domestic and imported materials.