USI Electric MICN109 Hardwired 3-in-1 Smoke, Carbon Monoxide and Natural Gas Alarm 3-in-1 alarm provides triple the protection with a single installation to protect against fires, carbon monoxide and natural gas 120-volt AC/DC hardwired alarm with backup battery is suitable for houses, apartments and mobile homes Mount the bracket to any standard wiring junction box and use the large mounting base to cover imperfections in drywall Features a quick activation pull-tab and a front-loading battery drawer for replacement without removing the alarm from the bracket Comes with a 7 year limited warranty