Install this First Alert® SMICO100-AC Hardwire Smoke and CO Detector as a single alarm or interconnect multiple, compatible ones together to create an alarm system throughout your home. All connected alarms will sound when 1 in the series is alerted to help provide an early warning. Integrate with up to 12 other First Alert® or BRK® alarms and 6 other compatible devices. Reference user's manual for compatible detectors. If the detector system sounds, the latching alarm indicator will visually identify the device that initiated the alarm. The SMICO100-AC includes an adapter plug to allow for easy installation or replacement of existing hardwire alarms. It is also equipped with a battery back to provide continuous protection during power outages. Help stop unwanted removal of the detector or backup battery using the optional locking features. Ensure the hardwire combination alarm is working properly using the single test/silence button located on the front of the device. A low battery warning will let you know when it's time to replace the backup battery and an end-of-life warning will let you know when it's time to replace the detector completely. See user's manual for information on how and when to test and replace detectors.