37C1: 17 x 18 mm. 37A1: 13 x 14 mm. IceToolz 37X3 37A1-37C1 Cone Wrench Repair Tools. IceToolz Bicycle Hub Cone Wrench Repair Tools is a slim shape open-ended spanner used specifically for bicycle repair and maintenance which enables them to access the confined area of the hub axle.
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