HM Digital pH Meter Model PH-80 Resolution: pH 0.1 pH, 0.00 - 14.0 pH. Accurate to ±0.1 pH. Hold button and auto shut-off. Automatic Calibration: Auto-ranging to 4, 7 or 10 pH. Very reliable and long lasting. Low battery indicator. Clear cap to notice moisture (or lack of) on probe. Glass encased reference electrode - helps retain moisture. Batteries included.