This is the mosquito countermeasure that is currently used by military personnel abroad. Proven to be up to 98% effective in repelling mosquitoes in field tests conducted by the Walter Reed Army Institute of Research, it uses d-cis/trans allethrin, a synthetic version of a naturally occurring insecticide found in chrysanthemum. Ideal for gardening, camping, or other outdoor recreation, the countermeasure slides into an included pouch equipped with belt loops and a sturdy clip for easy transport. A 2 1/2" x 1 1/2" mat saturated with repellent slides into a metal grill; a butane-fueled heater vaporizes the repellent to create a 15' x 15' zone unbearable for mosquitoes and other biting insects. Includes one butane cartridge and three ThermaCELL Mosquito Repellent mats. Butane cartridge lasts up to 12 hours; each mat lasts up to four hours. Not intended for use while worn. 8" H x 3 1/4" W x 1 1/2" D. (6 oz.)