I have two of these gauges, one is old and this one is new. I bought the first one because of the ANSI certification and it has worked great over the years. The new one seems equally stable on pressure readings, but the two gauges differ by about two pounds, about 7 percent. So which one is really accurate? Two pounds isn't much, and I'd probably be happy with either if I didn't have a comparison, but I expected ANSI certification to make them almost the same. The old one seems more consistent with the TPMS system in my car.