A precision CNC-machined aluminum tool for the installation & removal of select threaded bottom brackets with 16-notch tool fittings including Shimano Ultegra BBR60 & Deore XT MT-800 bottom brackets. Manufactured in-house by Park Tool anodized for easy identification & featuring a ratchet/torque wrench-compatible 3/8 drive. The BBT-59.3 features integrated threads for full compatibility with the Park Tool BBT-RS Bottom Bracket Tool Retaining System (sold separately). The BBT-RS uses an adjustable spring-based tension system to apply consistent adjustable pressure to the tool ensuring full engagement with the tool fitting & preventing slippage. BBT-59.3 FEATURES Fits 16-notch threaded bottom bracket tool fittings with a major diameter (outside of notches) of 41–42 mm & a minor diameter (inside of notches) of 39 mm including: Shimano Ultegra BBR60 Shimano Deore XT MT-800 3/8 drive fitting