Your Fit Kit extends the useful life of both your bottom bracket and your cranks, reduces the potential for noise, and also allows you to use one bottom bracket with a wide array of cranks, if that's your jam. Fit Kit #3 (PBB083) for ThreadFit(TM) 30 with 30mm spindle cranksets. For use with ThreadFit(TM) 30 68mm, 73mm BB shells. Common Cranks: White Industries, SRAM, Race Face