BPS

CX doesn't know how to list their arrows like a normal manufactuer would list them.BY SPINE.They are actually backward,meaning the 400 is the stiffest and the 100 is the weakest.Unless you are looking at the Medallion series and I think they are listed correctly.450 being the stiffest and 1000
being the lightest.(I think)

So the 400 wouldn't be underspined because it is the stiffest shaft they make.[]