Cassette Lockring or Freewheel Tool - FR-5.2 - from Park Tool USA
The FR-5.2GT has 12 splines that are approximately 23.4mm across, it is designed specifically for use when removing and installing cassette lockrings from thru axle hubs
It uses a 12mm guide pin to stabilise the tool when in use
Fits 12-spline cassette lockrings from Shimano , SRAM (including 1x), SunRace, SunTour, Chris King and others (23.5mm diameter)
Note: You will also need a chain whip tool to hold the cog in place.
Park Tool Reference: FR-5GT
Colour: Black