The two machined aluminium cups thread together ensuring the bottom bracket remains stable in the frame, increasing bearing life, and simplifying maintenance,This means no more creaking, smoother operation, longer bearing life, and really quick bearing replacement,Specifically designed for installing 24mm spindle diameter cranks (Shimano, Etc.) in Cannondale BB30A (42mm ID, 73mm wide asymmetrical BB shell) frames without the need for any adaptors,Note: FSA MegaExo spindles can be between 24mm and 24.07mm in diameter. If your FSA spindle is 24.07mm, this BB will not work.