Wind-Driven Turbine Exhaust Ventilator Bracing Location External Head Diameter 14 1/4 in Throat Diameter 8 in Airflow @ 4 mph 255 cfm Metal Material Thickness 24 ga 26 ga Overall Height 15 in Overall Width 14 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