Pressure pot Identification help needed, is it a brake bleeder or what??

[csapp05]

Got this from my dad, I remember seeing it from the possible late 70's into the 80's, but never seen it being used!
He was a certified/factory trained VW, Nissan, Mitsubishi, Porsche and Audi tech, so it could be specific to those marques.
Any ideas? Thanks!

 

[csapp05]

Also there are not any markings whatsoever on it, the T handle screws into the top, it not a pump handle.