Designed and tooled to perfection for the chimney professional, the DuraTech Chimney System sets a new standard in quality, design, and performance.Requires: 2 air clearance to combustibles for all diametersCollection: DuraTech Elbow by Angle: 30 (degree) Fuel Type: Coal, Oil, Wood Inner Wall: 430 Stainless, 0.02 Thick Insulation: Thermal Tech Blanket Joint Connection Overlap: 1-1 2 Joint Connection Type: Twist-Lock standard on all diameters Material: Galvanized Steel Outer Wall: 430 G-90 Galvanized Steel, 0.02 Thick, or 0.02 Galvalume Steel Pipe Class: Class A Pipe Inside Diameter: 5 Vent Construction: Double Wall