Wind-Driven Turbine Exhaust Ventilator Bracing Location External Head Diameter 12 3/4 in Throat Diameter 6 in Airflow @ 4 mph 147 cfm Metal Material Thickness 24 ga 26 ga Overall Height 14 1/2 in Overall Width 12 3/4 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