Bike converters from most manufacturers (Shimano, Sram, Sunrace) differ in the classes and types of bikes they are used on. The front cross-link performs the function of moving the chain along the stars of the system, the rear cross-link moves the chain along the stars of the cassette. The front derailleurs may have an upper link arm and a lower link arm. They are also in different ways compatible with the sprockets of the system, therefore, when choosing the front derailleur, you should pay attention to how many teeth the sprocket of the system has. When choosing a rear crossover, you also need to consider the number of cassette stars, since different derailleurs have different travel ranges. The rear crossover must be in the same class with the cassette and chain, the higher the transmission class, the more complex the device and the less variations in the combination of speed derailleurs of different classes. But crossovers from different manufacturers (Shimano, Sram, Sunrace), which are on the same class level, are perfectly interchangeable, combined with the transmission. Front and rear crossovers from different manufacturers are perfectly combined with each other if they are in the same class. If you want to modify your transmission, it is always best to consult a specialist, as different combinations may have their own pitfalls.