Superpro / Supervent chimney pipes by Selkirk are constructed using 304-alloy stainless steel for both inner and outer walls, and specially formulated mineral wool insulation to reduce chances of corrosion.
Double coating process on components like flashing have twice the corrosion resistance of standard galvanized parts. Locking bands are recommended at the straight joints and required at elbows, joints between elbows, and tee connections. Selkirk chimney pipes' outside diameters are 2" larger than the listed ID size of the chimney.