This is simple-constructed couplings with cushioning rubber ( nitrile rubber) between two hubs. The AL model is a lightweight and low inertial model using aluminum alloy for the hub material. Due to the simple construction inserting a spider in a hub, engaging and disengaging can be easily performed by moving the device in an axial direction. In addition, centering can be easily performed by applying a straight edge to the outer circumference of the hub. A simple construction achieves a low price.