Woodstock W1037 5-Inch to 4-Inch Reducer
We engineered the inside diameter of the 2-1/2-Inch side of each of these fittings to duplicate the 2-1/2-Inch opening on your shop vac. Insert the shop vac brand hose to the vac and the other end to one of these fittings to power the dust collection system. The outside diameter matches our standard dust collection hose to function as regular reducers.