ITEM NAME:6.35mm to 6.35mm CNC Stepper Motor Shaft Coupling Coupler for Encoder J2C2 6.35mm to 6.35mm CNC Stepper Motor Shaft Coupling Coupler for Encoder J2C2 Product Name : Motor Shaft Coupler;Material : Aluminium Inner Diameter : 6.35mm / 1/4", 6.35mm / 1/4";Total Size : 20 x 25mm / 0.8" x 1"(D*H) Color : Silver Tone Weight : 18g Made from aluminium to reduce inertia. The CNC motor shaft coupler provides an extremely tight grip without marring the shaft. The coupler also includes grub screws for shaft flats. Pacakage Content : 1 x Motor Shaft Coupler Note:Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.