Klein Tools ET180 Digital Manometer, Air and Gas Pressure Tester, Differential Dual Port Pressure Gauge, Large LCD Display with BacklightMEASURE STATIC AND DIFFERENTIAL pressure from two ports in air and gas systemsMONITOR AND TROUBLESHOOT problems in HVAC Systems with a range of +/- 60 inH2O and full scale accuracy of +/-1.5-PercentSTRONG MAGNET ON BACK secures manometer for hands-free operationELEVEN UNITS MEASURED: Easily toggle between inH2O, bar, oz/in2, psi, mbar, kPa, inHg, mmHg, kg/cm2, ftH20, and cmH2OLARGE BACKLIT LCD provides easy viewing in low light conditions and shows values when toggling between minimum, maximum and average