The Universal 50646 Suction Relief Valve is for use with Cen-Tec 3200 Series hoses. It covers a hole in the metal tube extending from the hose handle and the valve can be opened to reduce suction when vacuuming curtains, draperies, upholstery and other areas so the cleaning tool can be moved more easily.
Cen-Tec hoses were also sold under the Vacu-Maid, Imperium, Vacuflo and other brands.