... Pen type digital pH meter, all in one, pH electrode is included, easy to use* Data hold function for freezing the desired value* Water ... fish hatcheries, food processing, photography, laboratory, quality control, school & colleges, swimming pools, water conditions* Auto calibration for pH 4.01, ... pH & temperaturesize : 20 mm x 27 mmPower supplyDC 1.5 V battery (LR44, BAT ) x 4 PCsOperating HumidityLess ...