This TPI Whole-House Attic Fan reduces your summer cooling costs. Open the windows and let the fan pull hot air from your home and exhaust it out through the attic. U.S.A. Diameter in. 30, Speeds qty. 2. Two-speed motor to maximize airflow Shutters automatically open when in use and close when turned off Can be installed without cutting joists Fan mounting dimensions 34in. x 35 1/2in.