Dust Extraction Fitting, Funnel Reducer, 4" x 2-1/4" - Vacuum And Dust Collector Ducts - Amazon.com
WEN 2-1/2 in. to 1-1/2 in. Cone Reducer Attachment for Dust Hoses and Dust Collection Systems DCA002 - The Home Depot
BUCKTOOL 1.2 HP Auto Start 750CFM Dust Collector with 3 Dust Collection Bag, 5.4 Cubic Bag Capacity and 5 PCS Reducer for Woodworking DC50 - Amazon.com
WoodRiver Dust Connection - 4" to 2-1/2" ABS Reducer Fitting for Dust Collection System
Amazon.com: Dust Collection Cone Reducer 4-Inch to 2 1/2-Inch plus Shop Vac Adapter and Versatile Rubber Adapter : Tools & Home Improvement
WEN 4 in. to 2-1/2 in. Cone Reducer Attachment for Dust Hoses and Dust Collection Systems DCA001 - The Home Depot
Amazon.com: Universal Vacuum Hose Adapter Kit Reducer Attachment Set Converter from 1 1/2 inch to 1 1/4 inch from 1 3/8 inch to 1 1/4 inch Dust Hose Port Adapter : Home & Kitchen