It seems dead accurate at around 110psi. But at about 25 psi and 35 psi drops it seems about 2 psi higher. It seals well and is repeatable. I'm working on my inner duals. It also reads perfectly through fill valve covers (and not all gauges). It's surprisingly big and solid. Minimum stick pressure 10psi. This is my first day with her; time will tell how it holds up.