This principle is the extension of the external traction tool. The principle of this tool is to extend the external traction, the specifications of this tool almost cover all motorcycle bearings, thank you, if it does not work for you, do not worry, please return it. Put the tool head into the inner ring of the bearing, then screw into the shaft. The tool head to open, and hook the inner ring of the bearing. Then rotate the shaft. Note: The data are all measured manually, please allow 1-3cm error due to differences in light and display, there may be some color differences, please refer to the actual item received.