ID those fittings!

I'm trying to plumb my stoopid adjustable prop. valve to fix my brakes and can't get the right fitting! I keep taking it apart after work and finding out that I don't have the right fitting after it's too late to get another. So I gotta put it back together and take another guess tomorrow.
Anyway... it's the fitting, closest to the radiator, that goes from the master cylinder to the proportioning valve. I'm guessing it's metric because it's not 3/16 or 1/4, and I couldn't tell if it was a regular flare/inverted flare fitting. Can anybody help?
TIA,
Billy

I can tell you that it's metric, but that's about all I can tell you.

Thanks Eagle... anybody else?