The REGALâ„¢ Series 3000 Gas Detectors are designed to accurately sense the presence of chlorine and/or sulfur dioxide in an enclosed environment. In the event of a possible gas leak, the Series 3000 detectors continuously display the concentration level(s) in PPM (parts per million) while simultaneously indicating the highest level detected on an LED bar graph. The REGALâ„¢ detectors are available in both single and dual sensor models. Models 3001 (CL2) and 3003 (SO2) are single sensor detectors and Models 3002 (CL2), 3004 (SO2) and 3005 (CL2and SO2) are dual sensor.