DuraVent, 12DCA-VCSS, Class A, 12 Inch DuraChimney II, Vent Pipe, Chimney Cap, The DuraChimney II 12" Class A Chimney Pipe Chimney Cap is a component that is used in a typical venting installation. The DuraChimney II is used to terminate chimney system. Required on all installations. Slides over previous section of DuraChimney II pipe to allow for chimney height adjustment. Includes Spark Arrestor. Features: Use to Terminate Chimney System Required on All Installations Overall Height: 31" Top Diameter: 24" Bottom Diameter: 15" Includes Spark Arrestor DuraChimney II is an exceptional factory-built alternative to pre-fabricated masonry chimneys. DuraChimney II is a unitized, lightweight design which eliminatesthe need for field assembly of pipe sections, allowing for faster installation. DuraChimney II is designed to stay cool on the outside, to provide a hot draft on the inside and to provide a fire-safe design that protects both the chimney and the building. The double-wall, air-cooled design allows the chimney to expand both radially and lengthwise under high temperatures.