Inside Diameter : 6 In. Length : 18 In. Outside Diameter : 8 In. Stainless Steel Thickness : 0.012 In. Coupler Size : 0.016 In. Material : Stainless Steel Insulation Density : 23 Lb./Cu. Ft. Temperature Rating : 2100 F Clearance To Combustibles : 2 In. Grade : UL Listed For Use With : Model SSII