Fits Nutone inlets that are square. Also fits Vacuflo proprietary 4940 inlets. Adapter screws (reverse threaded) onto the corrugations of the hose. It can also be used on upgraded hoses by pushing it directly on the hose end of any Low Voltage and Electric Hose. The advantages of using any upgraded how are a legitimate handle and the ability to use electricity to run an electric carpet grooming brush. With this hose end, suction begins when it is inserted into the inlet.