The First Alert SMCO100 Battery-Operated Combination Smoke Carbon Monoxide Alarm is equipped with First Alert's Precision Detection advanced sensing technology and meets new industry standards. This 2-in-1 smoke and carbon monoxide alarm provides reliable protection against both threats and is easy to install and maintain. First Alerts Precision Detection advanced sensing technology complies with new industry standards to reduce cooking nuisance alarms and provides early warning in the event of a home fire emergency Provides reliable 2in1 protection against both smoke and carbon monoxide Batteryoperated alarm allows for easy installation and maintenance Testsilence button for efficient testing to ensure alarm is working properly Endoflife warning lets you know when its time to replace the alarm