A cost-efficient standalone sensor & monitor for smaller underground garages with ventilation control, the Z-Gard COmbo Gas Monitor uses a solid-state sensor to detect carbon monoxide. The unit features local audio/visual alarm status indicators and it can be configured to interface with air-handling equipment to control air quality within a building. Additional remote sensors can be attached to the unit via the RS-485 network port, while a 4-20mA output is proportional to the calibrated operating range. Z Gard COmbo monitors have a single RS-485/single 4-20mA output and can be linked with upto 7 remote sensors using RS-485 only.