Features a built in adjustable low speed, designed for countinous 24 hours operation. Comes with a 5 position selector switch that is factory set to provide 5 different air performances ranging from 80 to 140 CFM. 0.6 Sone. Detachable 6" metal collar which includes a light weight back draft damper. Brushless DC motor fans for long life. Dimensions 11 3/8" x 10 1/2" x 7-5/8". White Polymeric Grille with torsion springs.