The SHIMANO BB-MT501 bottom bracket for Hollowtech II provides better sealing and rotation to delivery high driving efficiency. English (BSA) threaded bottom bracketFits 68 and 73mm frame bottom bracket shellsFor use with MTBAluminum threaded cups Spindle Interface Type: SHIMANO Hollowtech IIBottom Bra5JJcket Shell I.D.: 1.37BB Shell Width (mm): 68 , 73Defined Color: BlackBB/Frame Interface: English 50323(5:5/5/23:ARI