Siemens QFA4171D ROOM RH&T SNSR, 4-20MA, 2%, DSPLAY, CERTSiemens QFA4171D ROOM RH&T SNSR, 4 20mA, 2%, DSPLAY, CERT This Q Series Outdoor Air Relative Humidity and Relative Humidity Temperature Sensor with LCD display monitors and transmits changes in humidity and temperature to the building control system. This unit is especially suited for HVAC applications where high accuracy and short response times for measuring relative humidity are required. It has a 2 percent certified accuracy, a 4 to 20 mA humidity