The RKI S2 series of gas sensor/transmitters from RKI Instruments provide reliable, cost-effective detection of common gas hazards. Available for LEL, H2 Specific (LEL and ppm), oxygen, H2S, CO, and a variety of toxic gases, the S2 series can be used either indoors or out, and are designed to be used with RKI controllers such as the Beacon 110, Beacon 200,Beacon 410, or Beacon 800, or with PLC/DCS systems.S2 sensors provide an extremely high degree of accuracy, quick response, and long service life. The plug-in design allows sensors to be easily replaced in the field without tools. Key Features: Available gases include LEL, H2S, CO, PPM H2, and CO2 Toxic gases include Cl2, NH3, SO2, HCN, and more Infrared sensor for combustibles and CO2 Hydrogen-specific LEL is available Patented water repellent sensor coating 4-20 mA output Explosion proof construction