This 3 Inch Pellet Chimney Attic Insulation Shield from the PelletVent Pro series is a Type B gas component and consists of the duralock system for a tight seal. Required for installations that pass through an attic to prevent insulation and debris from accumulating near the vent. Provides 1 clearance to combustibles.Finish: Stainless Steel Fuel Type: BioFuel, Oil, Pellet Length: 20 Material: Galvalume Pipe Class: Type L Pipe Inside Diameter: 3 Pipe Shape: Round Style: Contemporary Modern UL Listed: Yes Vent Construction: Double Wall Weight: 5