Model USI-2430 120 Volt AC Powered 130F (57C) Fixed Temperature Alarm. 9V Battery Back-up in event of AC power failure. Includes 9 Volt battery. Interconnectable up to 18 units (12 units must be smoke alarms). When unit goes into alarm, all interconnected units sound their alarm. Originating Alarm Feature so when heat is detected, the red LED flashes on the initiating heat alarm. Green LED indicator for AC power. Separate large size 5-5/8 in. (143mm) mounting ring. Attaches to any standard rectangular or octagon junction box and covers drywall cutout. Fast and easy installation. Test Button. 120 VAC (60 Hz) Power. Wire harness for easy connection. Loud 85 Decibel Horn. Five Year limited warranty.