The Park Tool BBT-59.3 Bottom Bracket Tool is a precision CNC-machined aluminum tool for the installation and removal of select threaded bottom brackets with 16-notch tool fittings, including Shimano Ultegra BBR60 and Deore XT MT-800 bottom brackets. Manufactured in-house by Park Tool, anodized for easy identification and 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 and preventing slippage. Fits 16-notch threaded bottom bracket tool fittings with a major diameter (outside of notches) of 41-42 mm and a minor diameter (inside of notches) of 39 mm, including: Shimano Ultegra BBR60, and Shimano Deore XT MT-800 3/8" drive fitting