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 the 8 inch to 4 inch pipe reducer increaser features a tapered design, to reduce air flow turbulence and reduce pressure loss, which suitable for HVAC, exhaust, and industrial systems 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 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 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 Features: Works seamlessly with round ducts in HVAC, kitchen exhaust, dryer vents, and machinery exhaust systems. The 8 inch to 4 inch air duct reducer is a practical adapter for retrofitting and upgrading ductwork. Rugged construction resists dents, UV exposure, and waterproof, making the 8 inch to 4 inch round duct reducer to be a good solution for demanding ventilation needs. Specifications: Material: galvanized steel Color: silver Type: 8 inch to 4 inch 1 Piece 8 inch to 4 inch duct reducer Notes: Manual measurement, please allow slight errors on size. The color may exist a slight difference due to different screen displays. PackageContents: 1*pcs 8 to 4 inch duct reducer Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.