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 - & plusmn 138mbar, 0 - & plusmn 55.4 inches H20, 0 - & plusmn 1410mm H20, 0 - & plusmn 2psi, 0 - & plusmn 0.138bar.