The B24 adapter allows you to use Shimano, Sram or compatible cranksets on a BB30 frame. Please refer to the chart for details. The B24 is CnC'd from two pieces of 7000 series alloy and threads together to give proper alignment, stability and prolonged bearing life. The B24 requires ITS OWN installation tool. You can order it with or without the tool (if you have already purchased one).