This Flex Trim Collar - 4 Inside Diameter from the PelletVent Pro series is a Type B gas component and consists of the duralock system for a tight seal. Use to connect PelletVent Pro rigid pipe to a masonry chimney with stainless steel flexible relining.Female end swivels to allow ease of connection Double wall construction UL ListedADA Compliant: No Collection: PelletVent Pro Finish: Black Fuel Type: BioFuel, Oil, Pellet Height: 8-1 2 Inside Diameter: 4 Material: Galvalume Stainless Steel Pipe Class: Type B Pipe Shape: Round Style: Contemporary Modern Vent Construction: Double Wall Weight: 3