Perfect-Prime AR1890 Professional Digital Air Pressure Meter & Manometer to Measure Gauge & Differential Pressure &plusmn;13.79kPa / &plusmn;2 psi / &plusmn;55.4 H2O Large LCD with backlight to measure gauge & differential pressure Measuring ranges 13.79 kPa / 2 psi / 55.4 H2O with high accuracy 0.3% in full scale 11 selectable scales & units: inH2O, psi, bar, mbar, kPa, inHg, mmHg, ozin2, FtH2O, cmH2O, kgcm2 Zero adjust & offset functions; Data Hold; Error codes for out of range indication MAX/MIN/AVG values with relative time stamps; Low power indication; Auto power off (can be disabled)