Additional Details ------------------------------ Product description: Type "B" OD Identifier = + 1/2" Installed Length 1-1/2" Less Listed Length Inner Wall Outer Wall Galvanized Aluminum For gravity draft vent LP or natural gas appliances 100 million BTU/hr max, 500 degrees max. Not for wall furnaces UL Listed Warranty 10 yr. Gift boxed 6rv-36 6" x 3