Motor shaft coupler is the common part of motor system. Generally, customer will choose encoder coupling according to motor shaft size. But in fact, encoder couplings are of different types for different applications. Flexible coupling and rigid coupling are the two main type. Flexible coupling means there is one part flexible in coupling. The flexible part connects the two hubs and ensures some variant in some range when coupling working. When using this type of motor shaft flexible coupling, it can reduce the accuracy requirement for alignment, facilitate testing, and have good damping function when the speed is not stable.