Wind-Driven Turbine Exhaust Ventilator Bracing Location External Head Diameter 22 3/4 in Throat Diameter 14 in Airflow @ 4 mph 700 cfm Metal Material Thickness 22 ga 24 ga Overall Height 19 3/4 in Overall Width 22 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