Definitely getting into details over my head now.
All I know if I blowed as bloody hard as I possibly could into it and could not get it to, er, pun-not-intended, pass air. But put it on the CO2 line and the CO2 would pass no problem (even at really low psi settings, although I still have to run mine at 18-20psi just to produce a consistent bubble rate). So, that, and the fact that it's still working four years later. I was going through those clear plastic check valves like crazy. Not that they're expensive but it's just annoying when they stop working and you have to replace them.