our 8 inch to 4 inch duct connector is made of galvanized steel, which is sturdy and not easy to rust, that can withstand bad environments, resists rust, and delivers long lasting performance in industrial, commercial, or outdoor applications the 8 inch to 4 inch pipe reducer increaser features a tapered design, to reduce air turbulence and reduce pressure loss, which suitable for HVAC, exhaust, and industrial systems raised edges on both openings of the 8 inch to 4 inch duct adapter provide a better grip for connecting ducts, and its crimped design on the small end of the duct to fit inside section of ducting easily, making them firmly connect and work stably the 8 inch to 4 inch duct reducer measures about 5.9 inches/ 15 cm in length, 0.02 inch/ 0.6 mm in thickness, ideal for connecting 8 inches and 4 inches duct systems to get a smooth transition; Please check the specification and size of the product before purchase simply insert the straight or flexible pipe, secure it with the steel clamp or foil tape for an airtight seal, the round pipe connector fitting is ideal for reducing leaks and maximizing system efficiency, Weight: 0.94027154743 pounds, Manufacturer: Aboiled