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Designed to allow the use of 1-inch forks with frames that have 1 1/8-inch integrated head tubesBox Two Integrated headsets feature an aluminum top cap, CNC-machined bearing cover, and split crown race with super-smooth rolling 45x45 bearingsIS42/25.4|IS42/26.4Black97g25.44226.445°/45°1-1/8` to 1`

 Box Two Integrated headsets feature an aluminum top cap, CNC-machined bearing cover, and split crown race with super-smooth rolling, precision 45x45 bearings IS38/25.4|IS38/26.4 Black 77g 25.4 38 26.4 45?/45? 1`