Dr care Digital pH Scale Auto Calibration which is come in pen type Immerse the Electrode in pH 6.86 Under Temperature of 25 degree Celsius Standard Buffer solution of Phosphate and gently shake the Electrode. Regulate the trimmer with a screw driver until the buffer solution value corresponding to the measurement temperature Obtained. Immerse the Electrode in pH 4.01 or pH 9.18 the Standard buffer Solution of borax and after about one Minute until the buffer Solution value corresponding to the measurement temperature is obtained.