The ACI Relative Humidity Room Series utilizes a thermoset polymer capacitive sensing element with a factory fi­tted hydrophobic ­filter to improve its moisture resistance. The sensing elements multilayer construction also provides excellent resistance in applications where dust, dirt, oils and common environmental chemicals are found. (For RH/Temp combination units, please see data sheet for temperature output specifications). The RH room sensors include on board DIP switches which allow the user to select the desired output signal and can be powered by AC or DC power sources. Single point ­field calibration can be performed by using the increment and decrement calibration DIP switches to adjust your curve up or down in +/- 0.5% increments with each toggle of the corresponding switches. These enhancements provide increased flexibility and outstanding long-term reliability without the need to replace the sensors in the ­field. There are two enclosure options in this series which should satisfy most commercial decors. Both enclosures feature four-way air flow to minimize self-heating. Three and Five-point NIST Calibration Certi­ficates are available and must be ordered separately when placing your order.