12 standard internally braced wind turbine attic exhaust vent - top only. Galvanized steel construction - mill finish. Co-polymer bearing system for quiet, long-lasting, and smooth operation. Adjusts to 6/12 pitch. Tested to ensure durability and performance in extreme temperatures and high winds. This exhaust vent requires adequate soffit intake vents. Top only. Base and riser is not included. Mill finish. Lifetime limited warranty.WARNING:This product can expose you to chemicals including Chromium which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information visit