HM Digital AP-2 AquaPro Water Quality Electrical Conductivity Tester, 0-9999 &micro;S Range, 1 &micro;S Resolution, +/- 2% Readout Accuracy Measures electrical conductivity (EC) and temperature. Automatic Temperature Compensation (ATC) Water-resistant housing Digital Calibration (push button) Auto-off function, data-hold function and low-battery indicator. The AP-2 Tester measureselectrical conductivity (EC) and temperature Measurement Range:0-9999 S The AP-2 has a push buttondigital calibration feature