This 120V AC/DC hardwired alarm is suitable for replacement or retrofitting homes with existing USI or Universal brand alarms (with battery drawer). Ionization alarms are more effective at detecting fast flaming fires to help keep your family, home and belongings safe. Fast flaming fires typically consume combustible materials rapidly and spread quickly. The alarm is interconnectable with up to (24) compatible devices including smoke alarms, carbon monoxide alarms, heat detectors and relays. When one alarm activates, interconnected alarms sound throughout the home, providing additional time to escape safely. Other features include single silence/test button, loud 85 dB alarm, and two tamper resistant locking features to secure both battery and alarm. Comes with a 3-year limited warranty.