WoodRiver® Dust Connection™ Funnel Reducer Dust Collection Fitting improves the efficiency of your shop vacuum powered dust collection system. This tapered reducer allows a smooth transition from 4" hose to a variety of fittings you may be using to connect to your shop vacuum. One side of the 4" to 2" Funnel Reducer Fitting fits inside most 4" dust collection hose, while the other side fits inside most 2" dust collection hose. Features: Specifications: What's Included: