12" standard externally 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. Base and riser is not included. Mill finish. Lifetime limited warranty.