This Shimano caliper mounting bolt has an M6 x 37.9mm thread and comes with a snap ring whose revised shape makes it compatible with the BR-M8100, BR-M8120, BR-M7100 and BR-M7120 calipers. In addition, the mounting bolt assembly, which also includes two washers, is still suitable for older XT, SLX and other disc brakes, replacing the Y-8G498020 set. The bolt is used in conjunction with the SM-MA-F180P/P2 brake adapter for post mount to post mount installation with 160 or 180 mm brake rotor.