This 4 Inch x 48 Inch Pellet Chimney Straight Black Length Pipe from the PelletVent Pro series is a Type L Biofuel Chimney Pipe component and consists of the duralock system for a tight seal. Features fully unitized, twist-lock construction in 3 inch and 4 inch diameters. Listed at 1 inch clearance to combustibles in the USA and Canada. It can be used in both vertical and horizontal installations. Stainless steel welded seam inner wall, combined with a galvalume welded seam outer wall. Pipe OD is diameter plus 58 inch . Galvalume or painted black outer finish. 12 inch length available with stainless steel outer (SS). To calculate installed length, subtract 1 12 inch from each length of pipe. Features: Type: Chimney Straight Pipe. Finish: Black. Pipe Class: Type L. Pipe Shape: Round. Series: PelletVent Pro. Outer Pipe Material: Galvalume. Vent Construction: Double Wall. Fuel Type: Biofuels, Oil, Wood Pellet. Inner Pipe Material: 444 Stainless Steel. Perfect Fit Construction Allows Ease Of Twist-Lock Connections. Specifications: Overall Dimensions: 6 inch (L). Inner Pipe Gauge: 30. Outer Pipe Gauge: 28. Pipe Inside Diameter: 3 inch . Specifications: Diameter: 4 inch Construction Materials: Laser-welded, double-wall pipe with an inner wall of .012 inch stainless steel and a .018 inch laser-welded galvalume outer wallClearances: 1 inch clearance to combustibles in the USA for appliances using wood pellets or oil. 1 inch clearance to combustibles in Canada for oil-burning (type L vent) appliances. 3 inch clearance to combustibles in Canada for wood pellet-burning appliancesListings: c-UL-us Listed to UL 641 (MH8381 and MH14420). ULC Listed to ULC S609, ULCORD C441 (CMH1439 and CMH1440)Twist-lock connection