Kidde Hardwired Smoke Detector, AA Battery Backup, Interconnectable, LED Warning Light Indicators, 4 Pack

DETECTS SMOKE: Sounds a loud 85-decibel alarm when smoke is detected - 3 long beeps with red LED light flashing in time, repeating.
HARDWIRED & 2 AA BATTERY BACKUP (Included): Operates on 120V AC wiring (installed in the ceiling) with 2 AA alkaline batteries that provide battery backup coverage during power outages.
ENHANCED SENSING TECHNOLOGY: Reduces false alarms often caused by cooking. Comprehensively tested to meet the latest UL standards, meets UL 217 9th Edition & FCC standards.
SELF-TESTING ALARM: Internal components ensure alarm is always operating as expected. Not a substitute for a manual push test, perform a button test once per week to verify alarm operation.
INTERCONNECT CAPABILITY: When one alarm sounds, they all sound, so you can get out faster. (Different models offer different interconnection options and requirements. See User Guide for more info.)
3 LED NOTIFICATIONS: LED lights indicate alarm status, green = normal operation, amber = operating error, red = smoke detected.
TEST & HUSH BUTTON: Makes it easy to test the 5-inch smoke detector and silence false alarms, should they occur.
10-YEAR LIMITED WARRANTY: Warranty begins when the alarm is powered on. If that date is unknown, it should be assumed that alarms should be replaced.