Occunomix HEAT PAX Hand and Foot Warmer, 6.1 in L x 4.84 in W, Iron, Water,Vermiculite, Cellulose, Activated Carbon, Salt, Orange (561-1100-10R)
$4.94
Literally "run on air. Simply open to activate. Last up to 11 hours with an average temperature of 135°F/57°C. Safe, non-toxic and odorless.