Designed and tooled to perfection for the chimney professional, the DuraTech Chimney System sets a new standard in quality, design, and performance.This product requires 2 air clearance to combustibles for all diametersCollection: DuraTech Fuel Type: Coal, Oil, Wood Inner Diameter: 5 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 Length: 48 Material: Galvanized Steel Maximum Temperature Rating: Rated for continuous use at 1000°, intermittent use at 2100° Outer Wall: 430 G-90 Galvanized Steel, 0.02Thick, or 0.02 Galvalume Steel Pipe Class: Class A UL Listed: 103HT, 103 Vent Construction: Double Wall