Model : #40 (08B) #50 (10A) #60 (12A). Number of teeth : 10T 11T 12T 13T 14T 15T 16T 17T 18T 19T 20T 21T 22T 23T 24T 25T 26T 27T 28T 29T 30T. The tooth surface of the sprocket wheel has been quenched by high frequency, which makes the hardness higher and the service life longer.
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