First Alert CO400 Battery Powered Carbon Monoxide Alarm for $17.95

First Alert CO400 Battery Powered Carbon Monoxide Alarm for $17.95.  Shipping is free on orders over $25.  If needed, use this Filler Tool to pad the order to qualify for free shipping.  Here is a screenshot fo your reference.  Note that you can also get the 3-pack for slightly less on a per unit basis.  This is a battery-operated carbon monoxide alarm that uses electrochemical carbon monoxide sensor. Two AA batteries are included.