Fit BSA Threaded (1.37 in x 24 TPI) bottom bracket shell with ID of 33.5-33.9mm and width of 68-73mm and crank spindle diameter of 24 mm (Shimano standard) or 22/24 mm (SRAM GXP standard). Please verify frame’s BB shell sizes and crank spindle diameter before purchasing. Sealed bearings deliver reliable performance and long service life O-rings to prevent water, dirt intrusion and achieve long service life Note: a 16-notch, 44mm OD bottom bracket tool is required to install the BB. The tool is not included. O-rings to prevent water, dirt intrusion and achieve long service life Introducing our BSA bottom bracket, designed to fit frames BB shell with a width of 68-73mm, ID of 33.5-33.9mm / BSA Threaded (1.37 in x 24 TPI) and crank spindle in 24mm diameter (Shimano standard) or 22/24mm diameter (SRAM GXP standard). The sealed steel bearings ensure reliable performance and longevity, while O-rings prevent water and dirt intrusion for extended service life. Please note that a 16-notch, 44mm OD bottom bracket tool is required for installation (not included). Verify your frame's BB shell sizes before purchase to ensure a perfect fit.