This 4 Pellet Wall Thimble with Air Intake from the PelletVent Pro series is a Type B gas component and consists of the duralock system for a tight seal. Allows outside fresh air for combustion through the wall thimble without having to cut a second hole into the wall. Comes with an insulation ring to reduce air infiltration where the pipe slips through the thimble.The 2 diameter, 18 length flex hose expands to 5' Clamps included Can be used in US and Canada PatentedADA Compliant: No Collection: PelletVent Pro Depth: 4 - 8 Finish: Matte Black Fuel Type: BioFuel, Oil, Pellet Inner Diameter: 4 Length: 13 Material: Galvanized Steel Pipe Class: Type B Pipe Shape: Round Style: Contemporary Modern Vent Construction: Double Wall Weight: 5 Width: 13