It is single phase and single winding non-insulating transformer that the primary and secondary windings are connected. So the size is small and the price is cheap but it used simple load as Lamp, Heater, Motor and Fan.
Please consider carefully because it may malfunction when use to noise sensitive appliance to various controllers, position controller, PLC Etc. The AC input voltage is applied, the power indicator LED operates in consideration of the safety of the consumer. It is easily mounted on DIN Rail.