Double Wall stove pipe is a connector pipe that links wood stoves to insulated chimneys This system features a black aluminized steel outer casing and heavy gauge stainless steel inner liner 1/4 in. air space between inner and outer pipes provides superior insulating value 6 in. clearance to combustibles Three metal screws supplied with each length For installed length, subtract 1-3/8 in. per joint Listed to ULC S641 and UL 103 standards Black