SELKIRK Sure-Temp Stainless Steel Insulated Pipe Stainless steel outer casing and inner liner. Double-wall pipe with solid pack insulation. Tested to withstand 2100 F degree Fahrenheit . UL Underwriters' Laboratories listed. This test helps to prevent product damage or structural hazard during brief periods of this excessive chimney temperature. Normal temperature is 1000 F. Pipe Data Minimum clearance to combustibles 2 . Stainless steel thickness Inner lining and outer casing .012 couplers .016 . Insulation density 23 lb/cu ft pounds per cubic foot . Insulated pipe lengths are furnished with a Locking Band preassembled with captured nut and screw . Length 18 , Inside Diameter 6 , Outside Diameter 8 , Stainless Steel Thickness .012 , Coupler Size 0.016 , Material Stainless Steel, Insulation Density 23 lb/cu ft, Temperature Rating 2100 F, Clearance To Combustibles 2 , Grade UL Listed, For Use With Model SSII, Pkg Qty 1