BRK has been the top choice of contractors in the commercial market for over 50-years. Marketed to builders, electrical contractors serving single family, multifamily, hotel/motel, RV and manufactured homes channels. The contractor-friendly product and packaging design sets the professional standard. Carbon monoxide (CO) is the leading cause of accidental poisoning deaths in America, yet many people don't know they are suffering from CO poisoning until it???s too late. Symptoms of carbon monoxide poisoning are like the flu and you might not even know you're in danger. The CO5120BN hardwire alarm detects the CO you can't see, smell or taste in the air. This alarm comes with 9-Volt battery backup, incase of a power outage. It also features a Test/Silence button to check if the alarm is functioning properly as well as silence unwanted or nuisance alarms. This First Alert CO5120BN Carbon Monoxide Alarm is an essential product in protecting your home and family.