At the highest point the grill projects only 1/2" down from the ceiling. The electronically balanced centrifugal blowerwheel assures maximum ventilation with minimum sound. Install using the adjustable hanging brackets for 16" centers. 4"metal duct collar with back draft. Motors are suitable for continuous operation. UL Listed over a tub or shower on a GFCI circuit. HVI2100 Certified. Housing Dimensions: 10-7/8" W x 9-3/8" D x 7-7/8" H.