The following specifications are listed on the package: Range 5-150 psi; operating temperature 0-100 degrees Fahrenheit; Accuracy +/- 2 PSI at 20-100 PSI, +/- 3 PSI at 101-150 PSI. As other reviewers have said, it works as it should. You don't have to turn it off or reset it in any way between measurements. Every time you press it on the tire valve, it automatically takes a new reading. It blocks that reading on the display, detects that the pressure has dropped to zero, and updates the display