Calibration solution set pH 4.01 / 7.00 + 3M KClpH value: 4. 01 7. 00 + storage solution 3M KCl, 250ml each Precise calibration: Accuracy of pH 0. 015 allows highly accurate calibration Easy recognition: Based on the colors, you can recognize the correct solution at a glance (pH 4: red, pH 7: green) The 3M KCl storage solution preserves the sensitivity and accuracy of the pH ORP electrodes Use immediately: Instead of dissolving powder in distilled water first, you can use this solution immediately