120VAC Hardwired Smoke Alarm with Battery Backup. 120VAC hardwired alarm wires directly into your homes electrical system with battery backup and mute button. Battery backup ensures alarm works even during power outages. Mute feature silences nuisance alarms from cooking smoke or shower steam. Single button also tests alarm functions. Easy access battery drawer: no need to remove alarm from ceiling to change battery. Interconnects with up to 12 other First Alert or BRK hardwired alarms. 10-year limited warranty. Smoke alarm meets UL standards. This smoke & fire alarm is for you if: You want alarms wired directly into your home’s electrical system with the added safety of a battery backup. You want to easily mute unwanted alarms with the press of a button. Where To Place Safety Smoke Alarms: One in every bedroom, and at least one on every level of the home.