> North American (or at least US) spec is 11 inches, European is 14 inches.
> If running a Propex you get better/more consistent results at 14.

Loren:

Just FYI.  With the current Propexes Karl shippes he notes
that they are "orificed" for US pressures.  The label still
seems to have the European standard pressure, but the serial
number or something has "/US" appended to it.

Only Karl could say when this change happened.

Richard