Bottom brackets have some of the highest torque specs of any component found on a bicycle. Despite this some bottom bracket cups feature tool fittings that allow mere millimeters of engagement which can be a problem when attempting removal or installation. Solution: the Park Tool Bottom Bracket Tool Retaining System. Used in conjunction with nearly any Park Tool bottom bracket tool the BBT-RS uses a spring-based tension system to apply consistent adjustable pressure to the tool ensuring full engagement with the tool fitting and preventing slippage.The BBT-RS can be configured for use with the vast majority of threaded and thread-together bottom bracket standards. The BBT-RS features an M8 threaded rod and a double-sided adapter nut with M12 and M15 threads allowing it to thread directly into any compatible cartridge bottom bracket. The M15 adapter can also be used to install any of Park Tool's nine aluminum bottom bracket tools all of which feature integrated threading for use with the BBT-RS.Washer diameter: 57 mm (2.25")Rod length: 175 mm (6.9")Rod threading: M8 x 1.0Adapter nut threading: M12 x 1.0 & M15 x 1.0