Mainly used for servo motors, spindle, step motor and so on.Wear resistant ,high hardness and excellent response.Super elastic torque can absorb vibration, appropriate a large torque transmission. Specification:Color: Silver ToneNet Weight: 50gMaterial: Aluminum AlloyFixed Type: ClampThread Size: M4Connection Diameter: 12mm to 15mm / 0.47 to 0.59 inchTotal Length: 35mm /1.38 inchOutside Diameter : 30mm/ 1.18 inch Package List:1x Flexible Shaft Coupler