The Park Tool BBT-79 Bottom Bracket Tool is a precision CNC machined aluminum tool for the installation and removal of 12-notch external bearing bottom brackets. Anodized for easy identification and featuring a ratchet/torque wrench compatible 3/8 drive. Park Tool BBT-79 Bottom Bracket Tool Features  The BBT-79 is a precision machined aluminium tool for the installation and removal of 12-notch external bearing bottom brackets with an outside diameter of 46 mm The BBT-79 fits Race Face Cinch, Zipp Vuma, Rotor BSA30, Hawk Racing BB3086, and others 3/8 inch ratchet/torque wrench drive compatible Made in the USA and covered by Park Tool's legendary limited lifetime warranty