DuraVent 46DVA-ADP 4" x 6-5/8" Inner Diameter - DirectVent Pro Direct Vent Pipe, Black Attaches to appliance outlet allowing pipe to easily connect or disconnect. For Vermont Castings appliances. Diameter: 4 ID x 6 5/8 OD. Construction Materials: .020 aluminum inner wall with .018 painted black galvanized steel outer wall. Direct Vent Pipe, Black.