Lomanco BIB-12 MILL Whirlybird Turbine Ventilator 12-inch whirlybird turbine ventilator ensures long life and no maintenance Reduces winter ice build-up and energy bills; withstands winds up to 147 MPH 21 air-foil curved vanes with rolled vane edges to deflect water Vari-pitch base adjusts to a 12/12 roof pitch Lifetime warranty