pH Meter Digital Acidity Meter pH Tester Soil Meter Tester for Plants Flowers Vegetable Acidity Moisture pH MeasurementTechnical Specification 1.Automatic Temperature Compensation0-50 2.Battery Type3X1.5VAG13 3.Environment0-50; RH95% 4.Dimensionsmm175*51*25 5.Weight77g PH Calibration PH Calibration Immerse the electrode in ph 6.86ph 7.00standard buffer solution of phosphateand gently shake it. Allow the reading to stabilize and with a small screwdriver turn the calibration trimmer until the display shows 6.86 or 7.00 Rinse the electrode with distilled waterand suck it with filter paper FAQ 1.Whether the electrode can be replaced Yes . replaceable pH electrode is general Usable with virtually any electrode that has the same connector 2. Is there any difference between these four mini digital display acidity meters The measuring range of these four products is the same, but the probe is different Multiple Colors Available