accurate air gauge for airbags

[goin2themountains]

I never even thought of it. Yesterday afternoon DS and I put a set of Firestone airbags on the pickup. Aired them up to 70lbs., checked for leaks, then was going to drop the pressure to 5-10lbs. Discovered my pickup air gauge only goes down to 20 lbs. which is a little stiff for riding empty. I checked Autozone today, but they weren't really much help on an accurate air pressure gauge for low pressures. What do you all use?