Features include 2-inches of Secura Pus(TM) high-temperature insulation. This insulation minimizes heat loss through the chimney walls and can withstand intense heat. The free-floating inner lining is attached only to the male coupler at the top, expanding and contracting freely with temperature fluctuations. The external casing carries the structural load. Made from high-quality stainless steel for superior corrosion and high temperature resistance.