Superior Moisture and odour control for good indoor air quality, Customizable fan speed with a Pick-A-Flow airflow selector (1 fan, 2 speeds), Whisper Quiet operation - <0.3 sones at 80 CFM and 0.4 sones at 110 CFM, Flex-Z Fast installation bracket for easy installation from below the ceiling. cUL approved for shower installation using a dedictaed GFCI circuit, For medium to large sized rooms, Fits joist size 2 inch x 8 inch or larger