Uxcell a13052700ux0257 6mm to 8mm CNC Stepper Motor Shaft Coupling Coupler for Encoder Product Name : Motor Shaft Coupler; Material : Aluminum Inner Diameter : 6mm / 15/64", 8mm / 5/16";Total Size : 20 x 25mm / 0.8" x 1"(D*H) Color : Silver Tone Weight : 18g Package Content : 1 x Motor Shaft Coupler