Inner valve springs

I saw the LSM when researching last night....$400 lol, no thanks. If I was a pro sure, but I'm on the other end of the spectrum.

Thanks, great idea, I have one and removed gauge, looks like it might work, but why remove Schrader valve? If I remove it all the air will come out(like a tire)??
The schrader traps air in the hose/gauge, that means it only lets pressure out of the cyl., not in...just leave the air hose plugged on until that cylinder's finished & move to next.