6" DuraVent DuraPlus Black Transition Anchor Plate 6DP-AP13X21 6" DuraPlus Black 13" x 21" Transition Anchor Plate is used with a Slip Connector and Hanger in chimney restoration to connect DuraLiner pipe to DuraTech DuraPlus or DuraTech Premium Chimney. Painted black. Diameter: 6" Dimensions: 13" x 31" Painted black .016” 430 stainless steel outer wall or .018” galvanized steel outer wall. .018” aluminized steel intermediate liner. .016” 430 stainless steel inner liner. Insulated layers plus ventilated air space. Locks tightly with a precision twist-lock connection.