... .pH electrode included Features:pH 6.86, pH 4.01 or pH 9.18, 3 points calibrationAuto calibration for pH 4.01, pH 6.86 or pH ... without operation in 20 mins.Available for wide applications, such as aquarium, beverage, fish hatcheries, food processing, photography, laboratory, quality control ... , school & colleges, swimming pools, water conditions . PT-6022 digital PH meter, Pen type digital ...