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.Machined from 4140 steel for heavy-duty workshop useEight-notch tool fitting with a nominal inside diameter of 37.6mm and outside diameter of 42.7mmExtra-deep body accommodates extra-wide spindlesLow-profile walls at the point of engagement reach recessed lockringsThree drive options: 3/8" drive fitting 1" hex fitting and 36mm wrench flatsInternal clearance: 31.14mm (1.226") depth x 22.48mm (0.885") diameterCompatible with Bosch Gen 3 Gen 4 and Gen 5 e-bike chainring lockrings and Specialized Levo Brose systemsNot rated for use with impact drivers