3 in 1 Waterproof pH / ORP / Temperature Meter Water Tester Oxidation Reduction Potential ATC mV &deg;C PH-099 3-in-1 to measure pH, ORP and Temperature Replaceable pH Electrode Built with Automatic Temperature Compensation (ATC) Calibration Powder (pH 4.003 & pH 6.864) included Easy to use with high accuracy