Check the listing for details. Duct Reducer Connector Adapter Air Ducting Pipe Vent Hose 6 Inch to 4 Inch. Condition: New. Listed at 19.08 USD. Pipe for air ductsWhy Choose This:★Outer Diameter: 150 x 100 mm / 5.91 x 3.94 inch (Big*Small); Size: 120 x 0.6 mm / 4.7 x 0.02 inch (Height*Thickness)★Easy to Install: Connect the duct reducer to a metal duct, vent hose, fan outlet, or inlet, use a pipe clamp, glue, or tape to secure the connection if needed.★Duct Reducer and Increaser: The vent reducer increaser is used as a duct adapter for reducing or increasing the diameters of an air duct, it's a useful duct fitting for changing your duct system to the needed size while maintaining smooth airflow.★Good Material: The duct reducer connector adapter is made of galvanized iron sheet, which is not easy to rust, is corrosion-resistant, durable, strong, and thick enough for the ducting system.