From the Manufacturer
Universal Security Instruments SS-770-LR smoke and fire alarm with battery back-up; a standard, large ring, 9-Volt battery-operated smoke alarm. Features include a audible low battery warning that sounds for up to 30 days to remind you to replace the battery. alarm power and test button, with a loud, 85-decibel horn. Ideal for replacement of most existing smoke alarms, offering fast and easy installation. The alarm carries a five year USA alarm warranty.
Craftmade SS770LR Smoke/Fire Alarm - Battery Only Operates on Battery Power Only (I-9 Volt Included)