AC/DC powered, ionization smoke alarm that operates on a 120V power source with 9V battery backup. This alarm uses ionization sensing technology. Ionization sensing alarms may detect invisible fire particles (associated with flaming fires) sooner than photoelectric alarms. Photoelectric sensing alarms may detect visible particles (associated with smoldering fires) sooner than ionization alarms. Features a front-loading battery door which allows user to change the battery without removing the alarm from the mounting bracket, making battery replacement easy and convenient UL Listed product with a 5-year limited warranty Hardwired Voltage: 120 Ionization Sensor Battery Back-up Decibel Level: 85dB 9V Batteries Included