Specifications Range: 0?4pH(pH) 0?/-1999mV(ORP) Accuracy: +/- 0.02pH +/- 1mV Stability: +/- 0.010pH +/- 1mV Temperature Compensation: Auto/Manual Alarm Output: Two Relays, 220V / 5A Electrical Output: Isolated and Optically Coupled Output, 4-20mA, Maximum Load is 550 ohm. Ambient Conditions: -10?5癈, 0-85% related humidity, non-condensing Power Requirement: 110V / 220V +/- 10%, 50/60HZ +/- 5% Enclosure Dimension: 96*96*110mm, (mode F) 65*130*160mm Mounting Dimension: 91*91*130mm Safe Class: IP55, (mode F) IP65