Size Details: the 5 inch to 4 inch duct reducer measures about 4.7 inches/ 12 cm in length, 0.02 inch/ 0.6 mm in thickness, ideal for connecting 7 inches and 4 inches duct systems to get a smooth transition; Please check the specification and size of the product before purchase Tapered Design: the 5 inch to 4 inch pipe reducer increaser features a precision tapered design, to reduce air flow turbulence and reduce pressure loss, which suitable for HVAC, exhaust, and industrial systems Sturdy and Long Lasting: our 5 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 Functional and Effective: raised edges on both openings of the 5 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 the next section of ducting easily, making them firmly connect and work stably Easy Installation: 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 5 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 5 inch to 4 inch round duct reducer to be a good solution for demanding ventilation needs. Specifications: Material: galvanized steel Color: silver Type: 5 inch to 4 inch 1 Piece 5 inch to 4 inch duct reducer Notes: Manual measurement, please allow slight errors on size