Universal Security Instruments USI-2430 120-Volt AC/DC Wired-In 135 Degree-Fahernheit Heat Alarm 135-Degree-Fahrenheit fixed temperature alarm ideal for heated garages, attics, kitchens, laundry rooms or other areas not suitable for smoke alarm installations The 9-Volt super heavy duty battery backup continues protection during a power failure The large 5-5/8-Inch mounting plate attaches to the junction box and covers drywall cutouts for easy installation Interconnect with other USI smoke or CO alarms up to 18 units, 12 smoke alarms maximum; when one alarm goes off all units sound their alarm The alarm sounds with its loud 85 decibel horn and the red LED indicator flashes. A green LED light indicates AC power