flex of shaft is measured by CPM.
but different manufacturers may classify or label the stiffness of their shafts at different ranges.
you can read this article for more details if technical details interests you. but DGman or another club fitter might be able to explain all this better and with more details.
Callaway Razr Fit Xtreme 10.5* Ahina 60 R
PRGR EGG Spoon 15* MRC Fubuki Alpha 70S
Adams Super Hybrid XTD 19* MRC Fubuki AH R
Adams A12 Pro 23* GD Tour AD UT85 R
Callaway X Hot Pro 5-PW PX95 5.5
Titleist SM4 50*, 54*, 58* DG Spinner
Scotty Studio Select 2012 Golo 33"