INVENT™ Series fans. Plug-in, permanently lubricated motor, engineered for continuous operation. Dynamically balanced centrifugal blower wheel for quiet, efficient performance. Low RPM for quiet operation. Rugged, 26 gauge, galvanized steel construction. Polymeric, 4 inch duct connector with tapered sleeve and no metallic clatter. 5-3/4 inch height allows for 2 x 6 inch ceiling installations. Sturdy, easy, four-point mounting directly to joist. Can be mounted in ceilings up to 7/12 pitch.