Employs "smart sensor” technology to monitor specific environment for combination of any (2) gases. "Smart sensors” feature automatic sensor recognition, zero and cal fault protection and access code security. Units equipped with optional on-board relays can operate as stand-alone monitors, activating alarms, horns or fans and shut down a system without needing to be hardwired back to a central control. Relay deactivation prevents accidental alarm activation during calibration. Features include bright dual-channel split-screen LED display, programmable alarms and on-board sensor life indicators. • Up to (2) detection points from a single head • Independent or multi-unit functionality via RS485 bus • 4-20 mA or ModBus RTU digital output to any control device or PLC • Approvals: NRTL/c, Class I, Divisions 1, 2, Groups B, C, D; CSA, Class I, Divisions 1, 2, Groups B, C, D.