Grabber Warmers, Mega Warmer, 10 pack. Rectangular, single-use, air-activated heat packs that are larger and last longer than standard heat packs. They provide up to 18 hours of continuous warmth for the hands and body. Averages 135 Degrees for 18 hours. Perfect For skiers, hunters, fishermen, golfers, campers or anyone who works or plays in the cold.