The Arctic Hayes Digital Differential Pressure Meter is ideal for domestic tightness testing. Has a digital back lit display that can show gauge or differential pressure in 11 different pressure units: mbar, psi, inches, H2O, bar, kPa, inHg, mmHg, ozin, ftH2O and kgcm. Other features include: a record function for holding measurements, max/min pressure feature, auto power off and a low battery indicator. Specification Pressure Ranges: 0 - ± 138mbar, 0 - ± 55.4 inches H20, 0 - ± 1410mm H20, 0 - ± 2psi, 0 - ± 0.138bar.