ThermaCELL pocket-sized, portable appliance repells up to 98% of mosquitoes, black flies and no-see-ums over a 15x15 foot area. No open flame. Perfect for decks, campsites, turkey blinds, tree stands and small boats. Undetectable to game. No DEET! Each appliance includes on cartridge and three mats for up to 12 hours of protection.