Now with patented Dual Fuel Technology. These heaters have the ability to use either Natural Gas or Liquid Propane in one unit. The ProCom Blue Flame Vent-Free Gas Space Heaters make supplemental heating fast and easy! Just push a button for easy ignition, stand back and enjoy a great source of dependable and affordable heat. These blue flame gas heaters heat the air first, circulating the warmth through the room, much like your central heating system.