TPI 597C1 Sling Psychrometer features small diameter tip (0.45 inch) for measuring dew point in air ducts and registers to prevent mold buildup, Measure dewpoint, humidity, and wet bulb temperature to prevent mold buildup and condensation in HVAC systems, Relative humidity (RH) accuracy of +/-2 percent provides accurate reliable readings, Temperature -40 degrees to 176 degrees F (-40 degrees to 80 degrees C), Fast response time, Data record function for maximum and minumum temperature or humidity reading, Serial output through RS 232C,39 inch cable length, hard wired,Data hold and Auto Power Off, Protective rubber boots.