The Abbey Bike Tools Crank Lockring Tool for Shimano bears a large hex that can be used with a 1.5” or 38mm wrench, or alternatively can be locked in a vice for ease of use.
Made to be compatible with chainring lockrings on Shimano single ring cranksets for 12 speed MTB drivetrains, it has been expertly machined by Abbey to engage precisely with a low-profile lockring, so it won't sheer off or mar the drivetrain you're working on. It can also be used to service XT and Ultegra bottom brackets with aplomb.