Spinning turbine ventilators are used for commercial and residential application to provide wind powered ventilation and increase air flow to the area below the roof line. Turbine vents require no power and their rotating tops use centrifugal force to suck air upward and expel it from the structure faster and more effectively than standard passive open air vents. HVAC Express turbine vents use jewel bearings for an increased lifespan and zero maintenance. Sizes available range from 4 inches and up to 48 inches for large commercial structures. (call for pricing on large turbines). Standard materials available are galvanized and aluminum. Call for stainless steel or copper turbine vents.