This Wolf Tooth Bottom Bracket Tool Is Precision Cnc Machined For Installation And Removal Of External Cup Bottom Brackets. Handmade In The USA At Wolf Tooth's Hq In Minneapolis.CompatibilityBbs3916: 16 Notch Bb Socket For 39mm Diameter Notch Pattern, Xtr/dura AceBbs4116: 16 Notch Bb Socket For 41mm Diameter Notch Pattern, Ultegra Bbr60Bbs4416: 16 Notch Bb Socket For 44mm Diameter Notch Pattern, Hollowtech Ii, Campagnolo, Chris King, FSA Megaexo, Hope, Sram/truvativ Gxp, Race Face X-type, Surly, Wheels, And OthersBbs4612: 12 Notch Bb Socket For 46mm Diameter Notch Pattern, Race Face 30mm Spindle, Tf47, Sram Dub, Raceface Cinch, Zipp Vuma, Rotor Bsa30, Hawk Racing Bb3086Bbs4816: 16 Notch Bb Socket For 48mm Diameter Notch Pattern, Fsa 386 Megaevo, Wheels® Pf30