Designed specifically for use when removing and installing cassette lockrings from thru axle hubs, the Park Tool Cassette Lockring Tool comes with a 12mm Guide Pin to stabilize itself when getting the job done. This tool fits 12-spline cassette lockrings from Shimano, SRAM, SunRace, SunTour, Chris King and others that are 23. 5mm in diameter. It also fits some Shimano and similar disc brake rotor lockrings.