Tamper resist feature unit goes into constant alarm mode if it has been unplugged or has come loose from the outlet;9V Battery backup provides continuous protection even during power outages;Test/Reset button tests the unit for proper operation and resets the Carbon Monoxide alarm;7-Year end of life warning alerts user to replace CO alarm after 7-years of operation (40% longer than other CO alarms);Kidde's carbon monoxide alarms meet the requirements of Underwriters Laboratories (UL), an independent facility that tests products for compliance with widely-accepted safety standards

• Kidde 900-0235 Nighthawk Carbon Monoxide Alarm, Long Life AC Powered with Battery Backup

Kidde 900-0235 Nighthawk Carbon Monoxide Alarm, Long Life AC Powered with Battery BackupKidde