The S300 common rail injector testing bench is a machine designed for testing and diagnosing diesel injectors. It is used to simulate the working conditions of a diesel engine and test the performance of the injectors. The S300 testing bench is capable of testing various types of injectors, including common rail injectors, piezoelectric injectors, and EUI/EUP injectors. The bench is equipped with various sensors and instruments to monitor and measure the injector's fuel flow rate, injection pressure, and fuel injection rate. The test results can be displayed on a computer screen and analyzed to determine if the injector is functioning properly or requires repair.