First Alert has been the go-to for home safety for decades. The SM210 skips the annual battery swap dance by sealing a lithium cell inside for a full ten years. That means no chirping at 2 AM and no forgetting to replace the backup power source.

The slim profile sits flush against the ceiling, which matters more than you might think. It avoids the awkward door-closing clearance issues of bulkier units. Precision Detection technology reduces nuisance alarms from cooking steam or shower humidity, so you aren’t silencing the thing every time you boil pasta. Installation takes two screws and a twist.

There is one honest trade-off: when the ten-year life expires, you replace the entire unit, not just the battery. That is the cost of never having to open it up. For most people, the peace of mind is worth it. This is a set-and-forget solution that does exactly what a smoke alarm should do.