Acumen Stopwatch Instruction Manual page 27

Range: 105 - 129
Range: 130 - 151
Note:
Our latest formula for Hydration and Heat Index are based on the Bodies
Radiant Temperature and the Humidity around the body. The values
shown on your watch when it is worn on the wrist are your Bodies
Radiant Temperature, Humidity around the body and the Body Heat
Index. To get the ambient temperature, humidity and heat index, please
remove the watch from the wrist and allow at least 15-20 minutes before
reading.
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