VENTILATOR & BASE TURBINE. WTE12X 12" Externally Braced Galvanized Turbine With Base, Mill, Ventilates Based On Wind. 345 CFM At 5 MPH Winds, 544 CFM At 8 MPH Winds & 969 CFM At 15 MPH Winds. Patented Dupont Delrin Bearings. Works On Roof Pitches 3/12 to 12/12.