· Ionization sensor technology senses invisible fire particles, while a electrochemical sensor detects CO gas· Smoke alarm operates on a 120V wired power source with a 10-year sealed lithium battery backup· An 85-decibel alarm sounds & a red LED indicates the smoke detector is sensing smoke or fire· Test-Hush button makes it easy to test the smoke detector and silence false alarms that occur from cooking or shower steam· Interconnection capability: allows you to connect up to 24 Kidde smoke, heat, or CO alarms, with the possibly it interconnect 6 strobe lights or relay modules· The unit will chirp at the end of the alarm life, indicating that the alarm is in need of replacement· UL Certified, 10-year limited manufacturer warranty