The BRK & First Alert 9120B was introduced in 2004 as a replacement for the 4120B [3]. The old plastic ionization chamber
with a metal top was replaced by an all metal chamber to shield electrical noise. The integrated circuit (IC) was upgraded. The BRK 9120
can be interconnected to other compatible BRK Smoke Alarms [2].
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Front of BRK/First Alert Model 9120 Box.
Back of BRK/First Alert Smoke Alarm Model 9120.
Inside the BRK/First Alert Smoke Alarm Model 9120.
Component Side of PC Board - BRK / First Alert Model 9120 Smoke Alarm.
Back Side of PC Board with Surface Mount Components- BRK/First Alert Smoke Alarm Model 9120.
Radioactive Source, Americium 241 - BRK / First Alert Smoke Alarm Model 9120.
Piezoelectric Disc - BRK/First Alert Smoke Alarm Model 9120.