1, Automatic Calibration, Auto-Buffer Recognition. 2, Message Indicator. 3, pH ... , ±1.8oF±1oC, ±1.8oFpH Calibration Points2 points2 pointsCalibration SolutionsNIST (pH4.00/6.86/9.18) or USA (pH4.01/7.00/10.01)NIST ... (pH4.00/6.86/9.18) or USA (pH4.01/7.00/10.01)Temperature Compensation0~100oC, 32~212oF, Automatic or Manual 0 ...