The HI9813-6 pH meter is an easy-to-use, water resistant, portable meter that measures pH, conductivity (EC), total dissolved solids (TDS), and temperature with a single probe. The HI9813-6 features the Hanna Instruments CAL CheckTM that will allow the user to know when the probe needs to be calibrated or replaced. The meter operation is simplified with dedicated buttons for measurement modes to be displayed on the LCD and knobs for single point calibration of pH and EC. A variable TDS conversion factor ensures that your results are right the first time. 3 in 1 probe with pH, EC, TDS & temperature sensors. CAL Check™ ensures the accuracy of this ph and ec meter. Great for hydroponics, aquariums, pools, & ponds.