Kaufhof KWY142 4 Inch x 2-1/2 Inch Threaded Adapter For Wood Shop Dust Collection Outer Diameter: 4 inch x 2-1/2 inch Length: 5 inch, replaces Big Horn 11418 Tapered male end for press-on fit Threaded end fits 2-1/2 inch outer diameter flexible hose Ideal for quick connection to 2-1/2 inch inner diameter machine dust ports