NPSP8WW Solar Power Fan, 800 CFM, 25" Diameter Metal Dome, Weatherwood, Ventilates Up To 1200 SQFT, Uses Solar Light To Operate, Comes On When Sun Is Up & Shuts Off When Sunlight No Longer Reaches The Panel, Must Be Facing To The West Or South For Best Sun Exposure, 12 Volt DC Motor, Needs 404 SQIN Of Net Free Intake Air, 14-1/2" Diameter Opening, 3 Bladed Fan Blade.