The ET180 Digital Differential Manometer from Klein Tools measures air and gas pressure for port 1, port 2, and measures the differential between the ports. Easily toggle between units: inH2O, bar, oz/in2, psi, mbar, kPa, inHg, mmHg, kg/cm2, ftH20, and cmH2O. Large, backlit LCD shows minimum, maximum and average values. Magnet on back for hands-free operation. Digital Manometer measures air and gas pressure for ports P1, P2, and differential. Range of +/- 60 inH2O and full scale accuracy of +/-1.5-Percent. Strong magnet on back for hands-free operation. Units measured: inH2O, bar, oz/in2, psi, mbar, kPa, inHg, mmHg, kg/cm2, ftH20, and cmH2O. Calculates minimum, maximum and average values. Large LCD is backlit for easy viewing in low light conditions. Auto-power off feature conserves battery life. Hold button locks current reading on the display. Silicon tubing, 3 x AAA batteries, and storage pouch included.