The Mantis is the world's most efficient and versatile direct vent fireplace. Its 90% plus efficiency rating, is only exceeded by the vent free gas technology. The Mantis uses approximately 35% less fuel versus other direct vent fireplaces in the market. It is the only fireplace available in the USA to use standard 1.5" PVC pipe for it's venting. The 1.5" PVC pipe can be run inside a conventional 2x4 framed wall. The Mantis is truly a unique fireplace that comes in three different forms: Bay Window, Traditional Fireplace (Insert), and G-Class Model. The Mantis is also the first and only direct vent fireplace that adds moisture to the home in addition to providing a source of heat.