"SELKIRK" METALBESTOS TOP *6" *Type B gas vent *OD = ID + 1/2" *Inner wall aluminum, outerwall galvanized *For gravity draft venting of "Listed" LP or natural gas burning appliances *100 million BTU per hr., 500 deg. F max. *Not for wall furnaces or woodburning applications *UL listed *10 yr. warranty *Boxed *#6RV-RT *6"