Wind-Driven Turbine Exhaust Ventilator Bracing Location External Head Diameter 10 1/4 in Throat Diameter 4 in Airflow @ 4 mph 126 cfm Metal Material Thickness 20 ga 22 ga Overall Height 12 in Overall Width 10 1/4 in Housing Material Steel Bearing Type Lower Thrust Ball Bearing Oilless Bronze Upper Bearing Bracing Material Aluminum Housing Finish Galvanized Includes - Installation Requirements Base for New Installations Flashing