Wind-Driven Turbine Exhaust Ventilator, Bracing Location External, Head Diameter 29 in, Throat Diameter 18 in, Airflow @ 4 mph 1,200 cfm, Metal Material Thickness 22 ga, 24 ga, Overall Height 24 in, Overall Width 29 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