Is the OPTIC inlet compatible with PAL SPME-Arrow?

Yes, OPTIC-4 is compatible with PAL SPME-Arrow but you need a special Top Boss.

Part Number: 2406-4185 OPTIC-4 Top Boss Assembly, Arrow, Standard Type (11 mm disc septa)

Part Number: 2406-4186 OPTIC-4 Top Boss Assembly, Arrow, Shimadzu Type (plug type septa)

This top assembly is needed for PAL SPME-Arrow. The Arrow needle has a bigger O.D. and for this reason a different Top Boss Assembly is needed.

Also available is a special Arrow liner.

And Merlin Microseal for SPME Arrow.