The ThermaCELL Outdoor Insect-Repellent Lantern is both a powerful insect repellent device and a functional, portable, long-lasting outdoor LED lantern, with both functions being usable separately or together. Providing a 15 by 15 feet mosquito-free zone, ThermaCELL says it is 98 percent effective (tested and used by the Department of Defense and the United States Army). It is also non-toxic, safe and non-intrusive, being DEET-free, silent, portable and odor free. Perfect for campsites, but also great for patios, backyards, decks, picnics and barbecues. ThermaCELL utilizes allethrin, an artificial version of a natural insecticide found in chrysanthemum flowers. The butane cartridge, which powers the mosquito repellent, provides 12 hours of power and is located on the interior for aesthetics and ease-of-use.