First Alert 1039758 Plug-In Explosive Gas/Carbon Monoxide Combination Alarm-(Each)

Electrochemical Carbon Monoxide sensor
Single Test/Silence Button
Backlit Digital Display for greater visibility of which hazard is being sensed (Gas or CO), the hazard level, and the peak level
3-Way Protection against Natural/Methane Gas, Propane Gas, and Carbon Monoxide
Low Battery Warning
End-of-Life Signal
5-Year Limited Warranty