The DuraTech 7-8 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. Made of aluminum.Bottom Diameter: 15 - 16 Finish: Stainless Steel Fuel Type: Coal, Gas, Oil, Wood Material: Galvanized Steel Pipe Class: Class A Pipe Shape: Round Style: Functional Top Diameter: 7 - 8 UL Listed: Yes Vent Construction: Double Wall Weight: 1