Dura/Plus chimney is designed for appliances that are tested and listed for use with a 2100°HT chimney system, such as wood stoves, fireplaces, furnaces, boilers, stoves, ranges, water heaters, or other appliances fueled by wood, oil, coal, or gas. Dura/Plus is tested to UL test procedures 103HT (2100°) and listed under UL re-examination service number MH 7399. You must use 100% Dura/Plus parts to obtain a Dura/Plus listed systemDura/Plus chimney pipe in 6 inch, 9 inch, and 12 inch lengths have a 1 inch insulating blanket. The 24 inch and 36 inch lengths have a 1/2 inch blanket. To calculate the installed length of Dura/Plus pipe lengths, subtract 1 1/2" from each length of chimney pipe. Dura/Plus Chimney is the metal chimney that does the three things a firesafe chimney must do! Stay cool on the outside, provide a hot draft on the inside, with a firesafe design that protects both the chimney and building. Dura/Plus chimney is designed for appliances that are tested and listed for use with a 2100°F HT chimney system, such as wood stoves, fireplaces, furnaces, boilers, stoves, ranges, water heaters, or other appliances fueled by wood, oil, coal, or gas. Specifications This product requires: 2" air clearance to combustibles for all diameters Connection Specs: Joint/Connection Overlap: 1-1/2" Joint/Connection Type: Twist-Lock standard on all diameters Material Specifications: Outer Wall: .016" Thick Stainless Steel or .018" Thick Galvanized Steel Inner Wall: .018" Stainless Steel Intermediate Wall: .018 Aluminized Steel Liner Insulation: Ceramic Blanket with Air Gap Misc: Maximum Temperature Rating: Rated for continuous use at 1000°, intermittent use at 2100° Supported Fuels: Wood, Oil, and Coal Warranty: 25 Years after date of installation UL Listed: 103HT, 103 Please Note!! All performance specifications and Warranties are contingent upon installation by a Licensed Contractor or Chimney Professional.