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, pools & spas, 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)