The DuraTech 12 Class A Chimney Pipe Storm Collar is required with DuraTech flashing to create a weather-proof penetration through the roof deck. Seal inner edge of the collar to the chimney pipe with non-hardening 500° F high temperature sealant.Required with DuraTech Flashing UL ListedBottom Diameter: 25 Collection: DuraTech Fuel Type: Coal, Gas, Oil, Wood Inside Diameter: 12 Material: Galvanized Steel Pipe Class: Class A Pipe Shape: Round Style: Functional Top Diameter: 14 Vent Construction: Double Wall Weight: 6 Width: 25