The Big Horn 11450 reducer’s small diameter of 2 inch duplicates the 2 inch opening on your vaccum. Insert the vaccum brand hose to the vacuum and the other end to one of these fittings to power the dust collection system. The larger diameter of the reducer matches our standard dust collection hose to function as regular reducers. These fittings provide a step down from a larger main line to smaller branch lines. This step-down increases air velocity near the machine where it’s needed most. This reducer connects to a standard 4 inch dust collection hose and should be secured with a hose clamp.