Rotronic HC2A-S Ambient Air Humidity Probe for Indicators, Transmitters or Dataloggers. The HC2A-S / HC2A-S3 is the most versatile probe from ROTRONIC and forms the basis of the product portfolio. It measures humidity and temperature and calculates the dew/frost point. Applications. HVAC. Food industry. Building services equipment. Paper. Textiles. Pharmaceuticals. Features. Relative humidity, temperature measurement and dew point calculation. Outstanding accuracy and repeatability. Excellent long-term stability ;1 %RH / year. Integrated data acquisition and calibration history. Auto-diagnostics with error compensation. Programmable alarm functions. Advanced easy-to-use calibration features. 100% field interchangeable