Vortex VTX1000S S Line S-1000 10 in Fan 1081 CFM, Black 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