| specifications | R817 | R827 | R837 |
| Temperature Range | -10℃~50℃ | -10℃~50℃ | -10℃~50℃ |
| Humidity Range | 10%RH~99%RH | 10%RH~99%RH | 10%RH~99%RH |
| Accuracy of Temperature | ±1℃±1.8°F | ±1℃±1.8°F | ±1℃±1.8°F |
| Accuracy of Humidity | ±5%(10~99%) | ±3%(30~99%) ±5%(10~30%) | ±3%(30~95%) ±5%(10~30%) |
| ℃/°F Selection | √ | √ | √ |
| Auto Manual Power Shut Off | √ | √ | √ |
| Low Battery Indication | √ | √ | √ |
| Data Hold | √ | √ | √ |
| Temperature Resolution | 0.1℃ | 0.1℃ | 0.1℃ |
| Humidity Resolution | 0.1%HR | 0.1%HR | 0.1%HR |
| Sampling Rate | 2times/sec | 2times/sec | 1.5times/sec |
| Max/Min Function | √ | ||
| Large LCD Temperature&Humidity Dual Display | √ | ||
| General Characteristics | |||
| Power | 9V Battery or DC Adapter | ||
| Product Weight | 170g | 194g | 194g |
| Product Size | 234mmx70mmx24.5mm | 207mmx70mmx29mm | 207mmx70mmx29mm |
Source: https://www.meterstesters.com/products/digital-thermometers/digital-humidity-and-temperature-meter-r827.html