The Extech RH350-NIST is a professional humidity and temperature meter offering superheat differential measurements such as T1-T2, Air-T1, and Dewpoint. It features dual Type K external temperature probe inputs and displays simultaneous readings of relative humidity, temperature, dew point, wet bulb, or external probe temperatures. The device includes a built-in RS-232 interface (with optional cable) for data transfer to a PC via Windows Hyperterminal, and it can store up to 99 data records. Ideal for use in laboratories, museums, mold-prone environments in commercial, retail, and residential sites, as well as HVAC/R and plant maintenance applications.