Park Tool BBT-18C cartridge key

Chainring lockring and cartridge bottom bracket tool, suitable for the chainring lockring of the XTR, XT, LX, and STX-RC cranks (from 1998) as well as the Ultegra and XTR bottom bracket cups [from 1998).

• Compatible with: Shimano® Octalink® right bottom bracket cup with external notches, Bontrager® ISIS Drive™ bottom bracket cups, front chainring lock for Bosch® Gen 3 and Gen 4 e-bike systems and Specialized® Levo® Brose® e-bike systems 
• can be combined with 36 mm wrench
• made from cast steel in workshop quality
• The BBT-18 has 8 notches with an outer diameter of nominally 43.4 mm
• The width from inside to outside is approximately 38 mm
• Each notch is about 3.9 mm wide
• The hole in the middle of the casting is 22.5 mm and does not fit over the 30 mm spindles