BRK has been making smoke alarms for decades. The SC9120B combines smoke and carbon monoxide detection in a single, battery-powered unit. That matters because carbon monoxide is invisible, odorless, and lethal—you won’t know it’s there until it’s too late. This alarm catches both threats without needing two separate devices cluttering your ceiling.

The unit weighs just 10 ounces, so installation is simple. It runs on batteries, but the specs say batteries aren’t included or required. That’s confusing: you’ll need to supply your own power source. In daily use, the alarm responds quickly to smoke from cooking or smoldering materials, and the CO sensor picks up dangerous levels from furnaces, gas ranges, or a running car in an attached garage. The test button lets you verify function without creating a real hazard.

The lack of listed features is a limitation here. There’s no mention of voice alerts, interconnectivity with other units, or a digital display for CO levels. It’s a straightforward, no-frills detector that does the basics well. For a basic safety upgrade, it works. If you want smart home integration or real-time readings, you’ll need to look elsewhere.