The air-activated Grabber MEGA Warmer last up to 18 hours to keep you warm. Only a few minutes after you open the packet these warmers will ease your shivers and keep you warmer no matter what you are doing.Contains 30 Individually Wrapped UnitsInstant Air-Activated HeatEach packet contains one warmerAverage temp is 135 F (57 C)Maximum temp is 166 F (74 C)Mega Warmer measures 4" x 5"Air-activated heatLasts up to 18 hoursMade in the USAUltra Warmers are perfect for skiers, snowboarders, hunters, campers, hikers, birdwatchers or anyone who enjoys outdoor activities when the weather is cold.