do you think the bubble rate will be stable with that ?I suspect it’s the older version of JBL’s basic regulator. It’s designed to fit both refillable and disposable (i.e. mounting nut can be changed). I think it will fit fire extinguisher if set up for refillable cylinders.
dual stage is better right ?The bubble rate will be stable as any other reg, it's the needle valve that controls the bubble rate rather than the reg itself, it's only going to be a single stage if that kind of things bothers you.