Help identify wood box/tool

[Silvr6]

I recently picked this wood box up from Goodwill. I noticed the slotted screws so I figured it was old. On the inside it obviously housed something, it looked like something was attached on the inside. There is also some directions typed onto a paper that is glued to the underside of the lid. From what I get from it, is that it's some kind of compression or leak tester. I've spent hours searching for something similar going off that assumption and have yet to find a single thing that resembles it. So I'm hoping someone might have an idea at what I have here.

[bigwull]

I would have thought that,....it was  quite obvious..what was in that box....An Airflow Regulator.....

[Silvr6]

well yes that is what I assume. I just dont know if this is a mass produced piece or if this is something someone put together in their garage and how old

[fancypants]

I'd say that yours was an case for a piece of testing equipment , probably used for testing a compressed-air compressor & associated pressure lines , for pneumatic controls used in commercial buildings (for HVAC systems) .
I'd guess that your little box was made no later than around the 1920's , perhaps one sold by Johnson Controls .

[bigwull]

take my advice....find something...anythin g, that will go into that box,....and tell yourself....Thats, the mystery object....cos...if you don,t, trying to find what might not now exist....will do your nut in.....