A 120V AC Wire-In Carbon Monoxide Alarm with Battery Backup provides worry-free protection for you and your family. It can be interconnected with up to 24 alarms (we recommend using connecting alarms made by the same manufacturer) throughout your home. All sound simultaneously if one is activated, providing you with full reporting for maximum safety. LED lights let you know the alarm is working. Press Test/Reset for periodic checks of battery and alarm operation or to silence non-emergency or nuisance alarms. 85-decibel alarm sounds loudly, alerting the household to a dangerous carbon monoxide level. For Deaf or severely hard-of-hearing individuals, look for our Strobe Light attachment, (sold separately) which easily connects and provides the important visual cue needed.