2-1/4" (57mm) x 2-1/2" (63mm) Dust Extraction Quick Coupler Fitting YW1088 by Oltre Screw End Adaptor allows you to attach a 2 ½" hose to it by just screwing the hose on, and then plug right into most any wet/dry vac and other standard 2 ¼" openings. No hose clamps are required.