DuraVent 46DVA-WG 4" x 6-5/8" DirectVent Pro Direct Vent Pipe - Galvanized Horiz, Galvanized Diameter: 4 ID x 6-5/8 OD. Construction Materials: Aluminum. Clearances: Specified by the appliance manufacturer. Listings: DirectVent Pro&#44; in combination with the gas appliance&#44; has been tested and listed as Use with through-the-wall termination cap where high winds are present.