| Specifications | 721939 | 721940 |
| Accuracy of mV (ISE) at 20°C/68°F | | ±0.2 |
| Accuracy of mV (ORP) at 20°C/68°F | | ±1 |
| Accuracy of pH at 20°C/68°F | ±0.01 | ±0.01 |
| Accuracy of temperature (°C) at 20°C/68°F | ±0.5° | ±0.5° |
| Battery Life | approximately 400 hours of continuous use; user-selectable auto-off after 10 mins of non-use | approximately 400 hours of continuous use; user-selectable auto-off after 10 mins of non-use |
| Battery Type | 4 x 1.5V AA | 4 x 1.5V AA |
| Electrode | BS4 72-1948 | BS4 72-1948 |
| Environment (RH) | 100% | 100% |
| Environment (°C) | 0° to 50° | 0° to 50° |
| Environment (°F) | 32° to 122° | 32° to 122° |
| Input Impedance | 1012? | 1012? |
| Meter Dimensions (H x W x D) English | 2.4 x 3.1 x 7.7 in | 2.4 x 3.1 x 7.7 in |
| Meter Dimensions (H x W x D) Metric | 60 x 80 x 196 mm | 60 x 80 x 196 mm |
| Offset Calibration | ±1 pH | ±1 pH |
| Slope Calibration | From 70 to 108% | From 70 to 108% |
| Temperature Compensation (°C) | Automatic or Manual from 0° to 100° | Automatic or Manual from 0° to 100° |
| Temperature Compensation (°F) | Automatic or Manual from 32° to 212° | Automatic or Manual from 32° to 212° |
| Temperature Probe | BS4 72-1949 with 1m (3 ft.) screened cable included | BS4 72-1949 with 1m (3 ft.) screened cable included |
| Temperature Range (°C) | 0.0° to 100.0° | 0.0° to 100.0° |
| Temperature Resolution (°C) | 0.1° | 0.1° |
| Typical EMC Deviation of Temperature (°C) | ±0.1 | ±0.1 |
| Typical EMC Deviation of mV (ISE) | | ±0.3 |
| Typical EMC Deviation of mV (ORP) | | ±1 |
| Typical EMC Deviation of pH | ±0.01 | ±0.01 |
| Weight English | 15 oz | 15 oz |
| Weight Metric | 425 g | 425 g |
| mV (ISE) Range | | ±399.9 |
| mV (ISE) Resolution | | 0.1 |
| mV (ORP) Range | | ±1999 |
| mV (ORP) Resolution | | 1 |
| pH Calibration | Automatic with 5 memorized standard buffers (pH 4.01, 6.86, 7.01, 9.18 or 10.01) | Automatic with 5 memorized standard buffers (pH 4.01, 6.86, 7.01, 9.18 or 10.01) |
| pH Range | 0.00 to 14.00 | 0.00 to 14.00 |
| pH Resolution | 0.01 | 0.01 |