The Shimano BB-MT501 Bottom Bracket for Hollowtech II provides a better seal and rotation to deliver high driving efficiency. Features: English (BSA) Threaded Bottom Bracket Fits 68 and 73mm Frame Bottom Bracket Shells For use with MTB aluminium threaded cups. Item Specifications: BB Shell Width (mm): 68-BB Shell Width (mm): 73-BB Frame Interface: English I.D. : 1.37-Defined Color: Black-Spindle Cut Type: Shimano Hollowtech II