The Extech RH300 hygro-thermometer psychrometer offers simultaneous display of %RH, temperature, and dew point or wet bulb. An external sensor is available for probe temperature readings. Weighing only 3.3 oz, it has basic accuracy of ±3% RH for humidity and ±1°C for internal and external temperature.

Features include data hold, auto power off, MAX/MIN readings, and calculation of T1-T2 differential using the optional probe and T2-Dew Point. The unique sensor cap design twists to closed position for protection during storage. Switchable °F/°C temperature units with 0.1° resolution. Powered by two AAA batteries. Ideal for HVAC, IAQ, and environmental monitoring.