Digital 3 in 1 ORP mv pH Temperature Meter Measuring Range: pH: 0.00 to 14.00pH / ORP/mV: 0 to 1999mV / Temp: 0C to 100C Accuracy : 0.1 pH / ORP/mV: 0.1% FS1 digit / Temp:0.4C Resolution: pH: 0.01pH / ORP/mV: 1mV / Temp:0.1C Operating Conditions: Room Temperature: 0C to 50C / Humidity: =95% Temperature Compensation: Completely automatic with ATC probe. When probe is off, temperature is fixed at 20C which can be modified with calibration screw.