USI Hardwired Ionization Smoke and Fire Detector with Battery Backup - 5304
Smoke Detector Fire Alarm, 2 Packs Photoelectric Smoke Detectors with UL Listed, 9V Battery Operated Smoke Detector (9V Battery Included), 10 Years Life Time, Fire Safety for Home, Hotel, School etc - Amazon.com
First Alert 9120B Smoke Detector, Hardwired Alarm with Battery Backup, 6-Pack - Smoke Detectors - Amazon.com