The TG Toxic Gas series offers Carbon Monoxide (CO), Nitrogen Dioxide (NO2), Methane (ch4), Propane (C3H8), Hydrogen (h2), Oxygen (O2), Hydrogen Sulfide (H2S), Ammonia, and refrigerant monitoring in a sensor/control format. The unit can also act as a stand alone controller, utilizing the relay for exhaust fan operation or the output for direct control of a VFD. The BACnet/Modbus model supports BACnet MS/TP & Modbus network communication in one unit. Standard features include network auto-configuration, a programmable fan relay, LED indicators, integrated display and audible alarm. Avaialable in rugged ABS or heavy duty metal enclosures. Now UL Listed and LADBS Approved (City of LA).