Set the duration and speed with the remote control from as far away as 45 feet, then hold on as the fan spools up to draw a massive 1400 CFM through the 5-micron primary filter and then through the 1-micron secondary filter. Fan speed options are 800, 900, 1000, 1100, or 1200 RPM. Changes the air in a 20' x 20' x 8' room 26 times an hour. Hangs easily from the ceiling. Three pocket internal filter bag simplifies cleaning. 5 speeds: 800-1200 RPM. Dimensions 30-1/8" x 19-7/8" x 16-3/8", weighs 73 lbs.