Siemens QFM3171 DUCT RH AND TEMP SENSOR, 2 PERCENT (HIGH) ACCURACY, RH: 4-20 4 T: 4-20 MASiemens QFM3171 Duct RH and Temp Sensor, 2 percent (high) accuracy, RH: 4 20 4 T: 4 20 mA This Q Series Duct Relative Humidity and Temperature Sensor monitors and transmits changes in humidity and temperature to the building control system. This unit is especially suited for applications where precise, stable humidity and temperature sensing is required. It has a 2 percent accuracy rating, a 4 to 20 mA humidity output signal, and a 4 to 20 mA