... accuracy .Less than 80% RHMicrocomputer circuit, intelligent function, high accuracyPower supply by 1.5 V battery (LR44 ) x ... 4 PCsAuto calibration for 0 mV, 500mVBuild in temperature sensor, ATC (auto ... , beverage, fish hatcheries, food processing, photography, laboratory, quality control, school & colleges, swimming pools, water conditions. PT-8022 ORP meter,Pen type ORP meter