At the highest point the grill projects only 1/2 in down from the ceiling. The electronically balanced centrifugal blower wheel assures maximum ventilation with minimum sound. Install using the adjustable hanging brackets for 16 in centers. 4 in 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 of 10-7/8 in W x 9-3/8 in D x 7-7/8 in H.