Portable gas heaters can be moved wherever extra heat is desired by carrying or rolling on included wheels or carts. They supplement heat from existing systems or can act as the primary source of heat in nonheated spaces. These heaters use natural gas or propane, and they're more heat-efficient than oil and kerosene heaters. Torpedo heaters are ideal for heating large ventilated enclosed spaces or open spaces. Ducted and tent heaters are used in large tented spaces or areas where the heat can be ducted. Table-top heaters are placed on work surfaces or floors for personal heating. Floor heaters are freestanding heaters that can be placed anywhere on the floor in small areas with limited space. Tank-top radiant heaters mount on standard DOT 20-lb or larger LP cylinders and provide radiant heat. Patio heaters stand above patrons and are used in restaurant, hotel, and retail patios as well as other outdoor locations. Portable heater accessories enhance the functionality of these heaters.