The EE80 Series transmitter measures carbon dioxide, relative humidity (rh), and temperature. This transmitter uses infrared gas detection to measure carbon dioxide; it has a measuring range from 0 to 2,000 ppm. The company says the patented self-calibration feature compensates for aging of the infrared source and ensures a unique, long-term stability for the CO2 sensor. Rh in the range of 10 percent to 90 percent is measured with the humidity sensor. According to the manufacturer, a built-in, state-of-the-art microprocessor ensures accuracy and long-term stability.