At the highest point the grill projects only 1/2" down from the ceiling. The electronically balanced centrifugal blower wheel assures maximum ventilation at the minimum sound. Easily installed using the adjustable hanging brackets for 16" centers. Motors are suitable for continuous operation. 4" plastic duct collar with back draft damper. UL listed for installation over a tub or shower on a GFCI circuit. HVI2100 Certified.