Specification:
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<br />Material: steel( electroplating)
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<br />Color:Silver
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<br />Inner Diameter: approx 12mm 
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<br />Size:approx 30mm*22mm(as the picture shown)
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<br />Widely used in hardware, tooling, mechanical transmission ect.
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<br />Package Including
<br />1 x 12mm Coupling Rigid Shaft Coupling Coupler