As my name suggests, they're a bit finicky, but once you type them in, they seem pretty accurate. A tip would be to use some blue Loctite on the threads once you have them where you want them as the locking ring seems to be quite loose. So the way these things work is that you have to do everything by trial and error. until the pressure drops to the desired level. Once you've done that, install the locking ring and the next time you screw it in they will depressurize to that value, so it's best to experiment with the installation BEFORE you leave home so that as soon as you're at the Once you arrive at your destination, you can screw it in and just wait, saving you a lot of time checking the PSI over and over again until it's done.