The Big Horn 11431 Reducer is ideal for professional and enthusiast woodworkers who work with shop vacuums or the equivalent. The 4 inch to 2 inch Reducer allows you to step down from a larger size hose or machine. The reducer connects 4 inch line to 2 inch dust ports or hoses. The step down increases air velocity where it is needed the most. With an outer diameter of 2 inch x 4 inch, this reducer lets you adapt to many machines. Connects to a standard 4 inch and 2 inch hose but must be secured using hose clamps.