Comfort Flame 18-8DM Chimney Pipe, 12-3/8 in OD, 18 in L, Galvanized Steel

Inner and outer pipe. The outer pipe, made of galvanized steel, provides cooling air necessary to maintain safe chimney temperatures, while the inner pipe, made of stainless steel, emits gases out of the fireplace. Snap- lock design. 12 in standard pipe (12 in ID, 15-3/8 in OD) UL127 Listed 1700 deg pipe.