The 1,081-cfm, 10-inch Vortex Powerfan S-Line is a revolutionary fan that combines energy efficiency, ultra-quiet operation and a collection of advanced technologies that deliver unparalleled performance. An extremely energy efficient AC brushless motor powers the patented mixed-flow dual impellers. Built with double-insulated walls, S-Line fans reduce noise to levels that were previously thought to be unattainable. All S-Line models are assembled with highly impact-resistant polycarbonate casings, an integrated backdraft damper, and a mounting bracket designed for quick and easy installation. S-Line models feature a 10-year warranty.