Get alerted to dangerous carbon monoxide leaks with the First Alert CO5120BN Hardwired Carbon Monoxide Alarm with Battery Backup. This carbon monoxide detector uses an advanced electrochemical carbon monoxide sensor that accurately detects elevated CO levels and comes equipped with a microprocessor that helps minimize false alarms. The alarm s plug-in power connector makes installation quick and easy while its tamper-resistant mounting bracket lock keeps the alarm secure. Featuring a 9-volt battery backup this unit is designed to offer seamless detection even in the event of a power outage. An 85-decibel horn sounds if carbon monoxide levels are too high and a warning chirp notifies you when the battery needs to be replaced. This carbon monoxide alarm can integrate with up to 12 other First Alert or BRK hardwired alarms and up to six other compatible devices--such as bells horns and repeaters--making it ideal for comprehensive coverage of large households or facilities. A latching alarm indicator automatically identifies which unit in the series triggered the alarm. And thanks to the convenient test/silence button the alarm can be checked easily to ensure it is functioning properly and false alarms can be muted easily.