This bottom bracket is for a BB30 shell. That means a bottom bracket that is non threaded and has a shell width of 68 mm and a inner diameter of 42 mm. For this bottom bracket we use the Rotor cups, they thread together in the middle of the shell to pull the system together securely in the frame. You can choose from black cups with your choice of steel, grade 5, or ZERO bearings or go with the red cups and either of the two ceramic options. No adapters needed to run your 24 mm crank spindle on your BB30 frame!