BQLZR 6.35mm x 12mm CNC Stepper Motor Shaft Coupler Flexible Coupling Motor Connector Shaft: 6.35mm x 12mm. Length: 30mm. Diameter: 25mm. Size: 3cm x 2.5cm x 2.5cm /1.18inch x 0.98inch x 0.98inch. This high quality shaft coupler is widely used to connect servo motor, stepper motor, encoder, screw driving, machine platform, etc.