The Extech RH401 is a Digital Psychrometer with a Built-in IR thermometer that allows quick non-contact surface temperature measurements. Displays air temperature, humidity and surface temperature or dew point, humidity and surface temperature or wet bulb, humidity and surface temperature on a triple LCD with backlighting. The IR thermometer features adjustable emissivity and a spot/distance ratio of 8:1. The meter calculates the temperature difference between IR surface temperature and dew point. Ideal for spotting potential areas with mold. Other features include data hold, programmable auto power off and a retractable probe that protects the sensors when the meter is not in use.