8" inch Vortex S Line S-800 Power Fan 728 CFM by Atmosphere + VenTech Variable Fan Speed Controller Includes Ventech Speed Controller and Timer for Maximum efficiency. The S-line is a revolutionary series of fans that combine energy efficiency, ultra-quiet operations and a collection of advanced technologies that deliver unparalleled performances. An extremely energy efficient ac brushless motor powers the patented mixed-flow dual impellers. Built with double insulated walls, noise is reduced to levels that were previously thought to be unattainable. All S-line models are assembled with high impact resistant polycarbonate casings, an integrated back draft damper and a mounting bracket designed for quick and easy installation.