Kaufhof KWY146 4 Inch x 2-1/4 Inch Threaded Coupler For Wood Shop Dust Collection Outer Diameter: 4 inch x 2-1/4 inch Length: 4.5 inch Tapered male end for press-on fit Threaded end fits 2-1/4 inch outer diameter flexible hose Ideal for quick connection to 2-1/4 inch inner diameter machine dust ports