• Simultaneous display of %RH, Temperature and Dew point or Wet Bulb or Probe Temperature
  • Wet bulb measurements without slinging
  • Calculates T1-T2 differential (Air Temperature-External Probe Temperature) using optional probe
  • Unique sensor cap design twists to closed position for protection during storage
  • Switchable °F/°C temperature units with 0.1° resolution


The Extech RH300 hygro-thermometer psychrometer offers simultaneous display of %RH, temperature, and dew point or wet bulb. An external sensor is also available for probe temperature readings. The handheld Extech RH300 hygro-thermometer psychrometer, weighing only 3.3 oz. (95g), has a basic accuracy of 0 to 100%RH (±3%RH) for humidity and ±1.8°F (±1°C) for internal and external temperature.

Other features of the Extech RH300 hygro-thermometer psychrometer include data hold, auto power off, and MAX / MIN readings. This Extech psychrometer can also calculate the T1-T2 differential using the optional probe and T2-Dew Point. The Extech RH300 hygro-thermometer psychrometer comes ready to operate with two AAA batteries.

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