Carbon Monoxide is a colorless, tasteless and irritant and toxic asphyxiating gas. It exists widely in the production and living environment. Carbon Monoxide (CO) Alarm is supplied with a powered–for–life sealed lithium battery. Using the unique house code feature, an interconnected system will sound all Alarms when one detects CO. The memory feature records the last CO alarm level and can be useful to check if CO has been present while the home owner or tenant was absent from the property. An easy to use Test/Hush button allows the user to check the Alarm.