[uloverun]1Pc flexible shaft coupling rigid for CNC motor coupler connectorProduct Description: Material: Aluminum Alloy Total Length: 25mm Outer Diameter: 19mm 5 Size for Choice: Shaft: 3*8mm Shaft: 5*6mm Shaft: 6*6.35mm Shaft: 6.35*6.35mm Shaft: 8*6.35mm Easy to install,buffer,damping,convenient to disconnect. Shaft coupler often used to connect servo motor, stepper motor, encoder, screw driving, machine platform, etc. The size is refer to the hole, for example, 3mm x 8mm means the hole diameter of one side is 3mm and the other side is 8mm. Package Included:1 x Motor Shaft Coupler Couplin