


🔥 Stay ahead of danger with smart, connected protection 🔗
The First Alert SA521CN-3ST is a hardwired smoke alarm featuring a photoelectric sensor optimized for detecting smoldering fires, wirelessly interconnecting up to 18 units for whole-home coverage, and equipped with a 2 AA battery backup to maintain monitoring during power outages. Designed for easy maintenance with a test/silence button and EZ access battery door, it combines trusted reliability with modern smart safety.
| Brand | First Alert |
| Style | Standard Detection |
| Power Source | Battery Powered |
| Color | White |
| Product Dimensions | 2"D x 5"W x 5"H |
| Item Weight | 10.4 ounces |
| Alarm | Audible |
| Sensor Type | photoelectric |
| Global Trade Identification Number | 00029054002440 |
| Number of Items | 1 |
| Manufacturer | First Alert |
| UPC | 029054002440 |
| Part Number | SA520B-SA521CN |
| Item model number | SA521CN-3ST |
| Is Discontinued By Manufacturer | No |
| Size | 1-Pack |
| Pattern | SA511CN2-3ST |
| Voltage | 120 Volts |
| Item Package Quantity | 1 |
| Number Of Pieces | 1 |
| Included Components | Electrical & Heating;Security and Intrusion Monitoring;smoke-detectors |
| Batteries Included? | Yes |
| Batteries Required? | Yes |
| Battery Cell Type | Alkaline |
| Warranty Description | 10 Years Limited |
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