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 great 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.