Extech RH350-NIST - NIST Calibration Certificate - Psychrometer Super Heat features:?áSuperheat differential measurements: T1-T2, Air-T1, T1-Dewpoint;?áDual Type K external temperature probe input;?áSimultaneous display of %RH, Temperature and Dew point or Wet Bulb or External Probe Temperatures;?áBuilt-in RS-232 interface, etc.