Plumbing ViAir Gauges

Okay I have some ViAir mechanical air gauges. How do you plumb them? Like what kind of fitting goes on the back side? They didn't come with any kind of instructions or any fittings, nothing. All thats on the back is the light port, and two studs (that hold the clamp onto the back of the gauge) that have a hole in them. I am assuming the fitting goes here, but I am lost as to what kind, or how? It just looks like 3/8" coarse thread.

its probably a 1/8" npt thread. i think that what they are on the kp gauges that ive used in the past.

honestly best bet would be to take the gauge with you to home depot and try something. its either 1/8" or 1/4" npt.

So I need a compression or PTC fitting with a female end that is 1/8" or 1/4" NPT? Someone told me I just needed the compression top, and it didn't make sense to me..

yea, you need a female npt to whatever connection type you like, either ptc or compression.

mine are 1/4" and i use compression

Well I searched all day, and finally found some 1/8" NPT female to 1/8" compression in a random box at Napa. If I didn't already have Ts with 1/8" fittings and 1/8" line I would have ran 1/4". I had no idea it was going to be so hard to find 1/8" fittings.

Seth I might have a few 1/8" female NPT x 1/8" compressions laying around, let me know if you still need any.

I found them at Napa.