DuraVent 6DVL-12ADJ 6" Inner Diameter - DVL Stove Pipe - Double Wall - 12" Pipe, Black DuraVent DVL is a double-wall interior stovepipe for connecting woodstoves to a manufactured chimney. Used for adding length to any DVL Double-Wall Black Pipe. Can be ovalized for oval to round appliance connector. Design reduces clearances to combustibles.