Carbon Monoxide and Nitrogen Dioxide standalone fixed sensor covers up to 9,000 sq. ft and can connect up to 2 additional remote sensors for expanded coverage. Can also be split in to 2 zones. The sensors have a 120V and 24V version. This device has 6 relays, 5A @ 125 VAC / 250 VA and Analog Outputs User-selectable 4-20 mA, 0.2-1 VDC, 1-5 VDC, or 2-10 VDC.