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. Application: Pulls hot air from the home and exhausts it out the attic, Diameter (in.): 30, Speeds (qty.): 2 Two-speed motor Shutters automatically open when in use and close when turned off Can be installed without cutting joists