Wind-Driven Turbine Exhaust Ventilator Bracing Location External Head Diameter 35 3/4 in Throat Diameter 24 in Airflow @ 4 mph 2 350 cfm Metal Material Thickness 20 ga 24 ga Overall Height 28 1/4 in Overall Width 35 3/4 in Housing Material Steel Bearing Type Lower Thrust Ball Bearing Oilless Bronze Upper Bearing Bracing Material Steel Housing Finish Galvanized Includes - Installation Requirements Base for New Installations Flashing