Introducing - The most efficient direct-vent gas fireplace product you can buy - so efficient, it uses PVC pipe for venting. The first and only condensing vented gas fireplace system certified for use in the U.S. A gas fireplace so unique, it takes multiple industry standards to certify it. The only vented fireplace system that also humidifies as it heats. The most advanced solid-state computer-controls on any fireplace - for even greater comfort, efficiency, and safety. The fireplace with the greatest installation flexibility. The Mantis puts the green in environmentally friendly. Its powered inlet/exhaust blower ensures the optimal air/fuel mixture for consistently clean-burning operation under any conditions.