If anyone wants to know:
According to Fram oil tech people the Fram C3P filters particles down
to 2 microns in size.
It is called a depth filter.
It is placed into a cannister.
It has a stacked plate design and traps smaller and smaller particles
as the oil moves further down towards where the inner plates meet.
On my boat with IH 392 it is run as a bypass filter.
So apparently it is a good filter to have.
It would be a poor choice to change to another design.
The only thing better is a submicronic bypass filter but if you have
the C3P this should be good enough.