Remember when you had a clean workshop? Connect your 2-1/2-inch dust hose to your 4-inch dust port with a WEN 4-Inch to 2-1/2-Inch Cone Reducer. This useful adapter installs easily, reducing the size of your woodworking tool's dust port from 4 inches to 2-1/2 inches. Inversely, this adapter also allows you to connect a 4-inch dust hose to a 2-1/2-inch dust collection port. The choice is yours. The durable ABS plastic construction provides maximum efficiency to your dust collection system when properly connected. The 4-inch connection side measures in at 94mm inner diameter and 100mm outer diameter, while the 2-1/2-inch connection side measures in at 58mm inner diameter and 63mm outer diameter. Compatible with WEN dust hose models 28200, 28221, DCA251, and DCA252. Remember when you had maximum suction? Remember WEN.