I bought two for my new water filter/softener install. The air bubble is quite large in these gauges, so it makes it hard to read if you want it vertical, and the pressure is 50-65psi. Out of the two I ordered, one read 70 psi, t he other read 65 with everything bypassed and nothing running, with another gauge reading 75psi. Not sure what is correct, but I would expect the two identical gauges to be the same, or within 1psi.