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The lowest price for First Alert 9120B / SMI100-AC Smoke Detector Hardwired Alarm with Battery Backup right now is $141.70 at desertcart.com.au, compared across 2 retailers.
The all-time low was $141.70 on 1 Nov 2026. That's the lowest price we've ever tracked — a great time to buy.
Prices last updated 1 Nov 2026.
First Alert 9120B / SMI100-AC Smoke Detector Hardwired Alarm with Battery Backup
Last updated at 01/11/2026 17:20:09
9120B / SMI100-AC Smoke Detector, Hardwired Alarm with Battery Backup, 3-Pack
Delivery between 8–11 Nov $29
First Alert BRK SMI100-AC Hardwired Smoke Detector with Battery Backup, 6-Pack
Delivery $39.36
| Detected Substances | Smoke |
| Sensor Type | Ionization |
| Detection Method | Ionization |
| Detection Range | Coverage of larger spaces |
| Certifications | UL standards |
9120B / SMI100-AC Smoke Detector, Hardwired Alarm with Battery Backup, 3-Pack
Delivery between 8–11 Nov $29
First Alert BRK SMI100-AC Hardwired Smoke Detector with Battery Backup, 6-Pack
Delivery $39.36
| Detected Substances | Smoke |
| Sensor Type | Ionization |
| Detection Method | Ionization |
| Detection Range | Coverage of larger spaces |
| Certifications | UL standards |
