1pcs BR 9.5mmx12.7mm D30L42 CNC Motor Shaft Coupler 9.5mm to 12.7mm Coupling connect servo motor stepper motor encoder BR series flexible coupling CNC Motor shaft coupler Body Material: Aluminum Alloy Max torque: 2N.m Rated Torque(N.m) :1N.m Eccentricity error: 0.2mm Shaft angel  2 Max Rotational (rpm) :19000 Rated: In-phase operate D=30 L=42 d1=9.5 d2=12.7