The COM-80 is an economically priced, reliable EC/TDS meter that is ideal for testing applications such as hydroponics & gardening, pools & spas, aquariums & reef tanks, water ionizers, drinking water and more. Measures electrical conductivity (EC), total dissolved solids (TDS). Excellent for nutrient testing. Four scales: EC:??S, mS; TDS: ppm, ppt. This tester has Automatic Temperature Compensation (ATC) and is water resistant. Measurement Range: 0-9990??S; 0-5000 ppm; 0-9.9 mS; 0-5.0 ppt. Digital Calibration (push button) to any point within the meter's range. Auto-off function, data-hold function and low-battery indicator with large and easy-to-read LCD screen includes simultaneous temperature reading. Factory Calibrated:?The COM-80 meter is calibrated with a 1413??S solution. The meter can be recalibrated with digital calibration using the push buttons. Includes a protective cap and batteries.