Park Tool BBT-4 Bottom Bracket Tool The BBT-4 is made for the installation and removal of 6-notch SC-S and AC-H cartridge cups used on sealed cartridge bottom brackets. These bottom brackets have six notches around the outside of each cup. The handle of the BBT-4 is vinyl coated for comfort. The major diameter of the tool is nominally 44mm, and the minor diameter 38mm. Features The BBT-4 is compatible with the following sealed cartridge bottom brackets: Campagnolo(R) Veloce Xenon Mirage Daytona Avanti Manufacturer's Part No: BBT-4 UPC: 763477000415 | Park Tool | Bbt-4 Bottom Braket Tool Campy Veloce, Mirage, And Centaur