Turbine Ventilator Throat Dia 6 in 147 cfm CFM @ 4 MPH Wind Overall Height - Roof Ventilators 14 1/2 in Overall Width - Roof Ventilators 12 3/4 in Bracing - Roof Ventilators External Construction Material Galvanized Steel With Aluminum Bracing Oiless Bronze Upper Bearing and Lower Thrust Type Ball Bearing Requires Base for New Installations Flashing Includes -