ORP meter with rugged flat surface OPR electrode and high resolution of 1mVFeatures:Measures ORP/Redox from -999 to 999mVAutomatic electronic self calibrationSimulated analog barograph displays change in ORP readingHigh resolution of 1mVMemory stores and recalls 15 readings and saves last calibrated valueData validation indicators show user the reading is stabilizedData Hold, Auto shut-off and low battery indication