Hi,
there are also similar DIN and ISO norms that mean the same. Please take a look at the table:
ABEC
I don't know if the ABEC is a most important factor for an IMS bearing. I think there are much more important factors like:
max rpm capacity
static load rating
dynamic load rating
maximum play
axial loadability
materials
type of sealing
Whereas i have to do more research to get into it. Also i have to research what kind of bearing exacty the Prosche IMS bearing is and why they used that type of bearing.
Regards Markus