FIRST ALERT BRK CO5120BN Hardwired Carbon Monoxide (CO) Detector with Battery -- The BRK hardwire carbon monoxide alarm detects dangerous CO gas and allows you peace of mind with its battery backup. Carbon monoxide (CO) is a colorless, odorless, deadly gas. It can be emitted by sources including gas or oil furnaces, gas clothes dryers, water heaters, fireplaces, wood stoves, charcoal grills, gas ranges, and space heaters. A clogged chimney, improper venting, and attached garages can also cause carbon monoxide accumulation. According to the Consumer Product Safety Commission (CPSC), at least one CO alarm should be installed near a home's sleeping area. This BRK alarm is perfect for bedrooms, as well as hallways, and basements. The BRK CO5120BN hardwire CO alarm with battery backup includes these features: Quick plug-in power connector for easy installation. 120-volt AC inter-connectable (with maximum 18 compatible devices). The alarm can be interconnected with up to 12 other compatible smoke alarms and six compatible devices like bells, horns, repeaters and door closers. If one unit triggers an alarm, all smoke alarms in the series will sound. Power indicators show which unit in the series initiated the alarm. Microprocessor controlled for fewer nuisance alarms. Single test/silence button which both silences a non-threatening alarm or low battery warning and allows you to test the unit's functionality. Automatically performs internal test of functionality. Latching alarm indicator which automatically identifies which unit initiated the alarm. Battery drawer lock and mounting bracket lock for tamper resistance. AC power indicator and alarm indicator light. Low battery warning "chirp" and missing battery tab. Swing open battery drawer for easy battery installation. 9-volt battery backup for peace of mind during power outages. All BRK Electronics carbon monoxide alarms are listed to UL Safety Standard 2034 for residential carbon monoxide alarms. Includes 9-volt backup battery. 5-year limited warranty.--Bree NorlanderWhat's in the Box One carbon monoxide alarm, one 9-volt battery, and user's manual Product Description 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. Features Plastic Imported 120 volt hard wired carbon monoxide alarm wires directly into your home's electrical system Electrochemical sensor accurately detects carbon monoxide Microprocessor controlled to minimize false alarms Easy to access battery drawer; 9 volt battery included Can integrate with up to 18 compatible devices for extended coverage; Emits T3 Pattern Faster turnarounds on job sites with the easy-to-install, most-trusted alarms in home safety USA SHIPPING estimates delivery times and we work to get your item to you as quickly as possible and within those times, but please know it may take slightly longer than the estimate.