The ThermaCELL Patio Lantern operates on a single butane cartridge, which heats a mat releasing allethrin, a synthetic copy of a natural insecticide found in pyrethrum flowers, creating a 15 x 15 foot comfort zone. Each repellent mat provides up to four hours of protection and each butane cartridge provides up to 12 hours of operation. Perfect for backyards, decks, picnics, barbeques, camping, and outdoor parties. ThermaCELL technology has been tested and approved by the U.S. Army. Currently used in Iraq, Kuwait and Afghanistan. An effective alternative to smelly lotions and sprays which must be applied to the skin. Easy to use: no open flame; no messy wax.