HMX 15MM barrel shaft conversion to 12MM mini barrel shaft, universal conversion seat Aluminum alloy material, light weight and high strength Can be used with the common 100*12MM road disc brake hub, which can be supported on the market It avoids the need to replace the hub when upgrading the front fork, which greatly saves money for bicycle enthusiasts 3-way seal ring design to the conversion seat, the hub is higher precision and stronger stability after installed Specification: Material: Aluminum Alloy Size: Approx. 30 x 15 mm / 1.18 x 0.6 inch Package Includes: 2 Pieces Barrel Shaft Conversion Seat Adapter (with 6 seal ring) Note: Due to the differences between different monitors, the picture may not reflect the actual color. There is 2-3% difference according to manual measurement, please check the size carefully before you buy the item. Thanks