PelletVent Pro 3″ Pellet Chimney Flex Pipe – 60″ This 3 Inch x 60 Inch Pellet Chimney Flex Pipe from the PelletVent Pro series is a Type L Biofuel Chimney Pipe component and consists of the duralock system for a tight seal. Use for offsetting rigid pipe around smoke shelf in masonry chimney only. Allows for offsets with biofuel appliances. Female and male ends twist-lock. Female end swivels for easy alignment. 60″ flex section. Not for use in attic or wall spaces. Features: Type: Chimney Flex Pipe. Pipe Class: Type L. Pipe Shape: Round. Collection: PelletVent Pro. Vent Construction: Double Wall. Outer Pipe Material: Galvalume. Fuel Type: Biofuels, Oil, Wood Pellet. Inner Pipe Material: 444 Stainless Steel. Specifications: Overall Dimensions: 60″ (L). Inner Pipe Gauge: 30. Outer Pipe Gauge: 28. Pipe Inside Diameter: 3″.