The Kidde FireX P12040 Hardwire inter connectable Photoelectric Smoke Alarm with Battery Backup can act as a stand-alone unit or can be integrated into an existing electrical system. This unit sounds an early warning to alert you and your family of the presence of visible fire particles detected by the alarm's photoelectric sensor. Powered by 120-Volt AC, this alarm protects you, your home and the people you hold dear even during power outages, thanks to a 9-Volt battery backup. A power harness facilitates an easy installation and a simple push of a button activates this alarm's test and hush features.. Alarm Sensor Type: Photoelectric. Alarm/Detector Features: Battery Back-Up,Hush Button. Alert Type: Siren. Commercial/Residential: Commercial,Home. Connector/Contact Type: 2-Wire. Fixed or portable: Fixed. Included: Batteries. Pack Size: 1. Power Source: Hardwired. Returnable: 90-Day. Voltage (V): 120. Certifications and Listings: UL Listed. Product Depth (in.): 1.55 in. Product Height (in.): 5.6 in. Product Width (in.): 5.6 in. Alarm Sensor Type: Photoelectric. Features: Battery Back-Up. Pack Size: 1. Features: Hush Button. Alert Type: Siren. Power Source: Hardwired