The GAF Master Flow 4500 CFM 24 in. Direct Drive Whole-House Fan is a smart energy saver for any home in a climate where air conditioning costs are a concern. It allows you to beat the heat by forcing hot air out of your home through your attic space while bringing in cooler outside air through your windows and doors. This unit comes with a white shutter and features a low-vibration, direct drive mechanism for reliable performance. A minimum 1100 sq. ft. of attic space with a minimum of 1008 sq. in. of net free area attic exhaust is required for proper operation.