The only handheld/portable TDS meter / EC meter with full scale digital calibration. A water tester that is perfect for both consumer or commercial use. Ideal for all water quality testing, water purification applications, wastewater regulation, aquaculture, hydroponics, colloidal silver, labs scientific testing, pool , ecology testing, boilers cooling towers, water treatment and more. Features Measures electrical conductivity (EC), total dissolved solids (TDS) and temperature. Three different calibration options (KCl, 442TM, NaCl), each with its own non-linear conversion factor. Automatic Temperature Compensation (ATC) using three temperature coefficients Waterproof housing Measurement Range: 0-9990 µS; 0-8560 ppm (auto-ranging). Digital Calibration (push button) Auto-off function, data-hold function and low-battery indicator. Display: large and easy-to-read LCD screen includes simultaneous temperature reading. Factory Calibrated: The COM-100 meter is calibrated with a 1413 µS solution. The meter can be recalibrated with digital calibration using the push buttons, rather than a screwdriver. Includes a cap, batteries and lanyard. Specifications EC Range: 0 - 9990 µS TDS Range: 0-8560 ppm (mg/L) Temperature Range: 0-80 C; 32-176 F Resolution: 0-99: 0.1 µS/ppm; 100-999: 1 µS/ppm; 1000-9990: 10 µS/ppm. Temp. resolution is 0.1 C/F Accuracy: +/- 2% EC to TDS Conversion Factor: Non-linear conversions for KCl, 442TM or NaCl solutions, set by the user. Calibration: Digital calibration by push button. Probe: Detachable platinum electrodes Housing: Waterproof (submersible) Power source: 3 x 1.5V button cell batteries (included) Dimensions: 18.5 x 3.4 x 3.4 cm (7.3 x 1.3 x 1.3 inches) Weight without case: 90.7g (3.2 oz)