The Park Tool BBT-118 Steel Bottom Bracket / Lockring Tool is a heavy-duty bicycle workshop tool machined from 4140 steel for removal and installation of components with eight-notch tool fittings. Suited for mechanics working across Shimano Octalink external cup bottom brackets ISIS Drive cups from Truvativ and Bontrager and front chainring lockrings on Bosch Gen 3 Gen 4 and Gen 5 e-bike systems as well as Specialized Levo Brose systems the BBT-118 covers a wide range of drivetrain and e-bike service tasks with a single tool. The extra-deep body accommodates extra-wide spindles while low-profile walls at the point of engagement allow the tool to reach recessed lockrings that shallower tools cannot access. Three drive options a 3/8″ drive fitting a 1″ hex fitting and 36mm wrench flats give the mechanic multiple engagement methods for tackling seized components. Internal clearance measures 31.14mm depth by 22.48mm diameter with a nominal inside diameter of 37.6mm and outside diameter of 42.7mm at the eight-notch engagement.