Range: WPH-10: -1.0 to 15.0 pH; WPH-20: 0.00 to 14.99 pH; WPH-30: -10.00 to 15.00 pH; Temperature: 0 to 50°C (32 to 122°F).Accuracy: WPH-10: ±0.1 pH; WPH-20 and WPH-30: ±0.01 pH.Display: 4-digit, 5/16" (8 mm) high LCD.Resolution: WPH-10: 0.1 pH; WPH-20 and WPH-30: 0.01 pH.Ambient Operating Temperature: 0 to 50°C (32 to 122°F).Power Requirements: (4) 1.5 V LR44, alkaline batteries, installed functional, user replaceable.Calibration: WPH-10: Up to three points USA/NIST buffers (4.0/4.0, 7.0/6.86, 10.0/9.18); WPH-20 & WPH-30: Up to 3 points US/NIST (4.01/4.01, 7.00/6.86, 10.00/9.18).Enclosure Rating: IP67.Electrode: Replaceable double junction.Weight: WPH-10: 7.2 oz (200 g); WPH-20 & WPH-30: 4.5 oz (125 g).Agency Approvals: CE.