Twin wall insulated flue system specifically designed to operate continuously with temperatures up to 450°C. Certified for corrosion resistance on gas, oil, wood and solid fuel, 4 hour fire rating to BS 476-20 and ‘soot fire’ resistant. Twist-lock bayonet jointing system, secured by a locking band. Inner casing is constructed from laser welded 316 L stainless steel, outer stainless steel 304.