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.