The Fist Alert SA3210 Dual Sensor Ten Year Alarm makes use of both ionization and photoelectric sensors to offer the earliest possible warning--regardless of the type of fire. While all smoke alarms ...

Think of buying the Roost Smart Smoke Alarm like buying a dumb alarm packaged with a smart battery. If you need both, it's worth a purchase, but if you only want smarts, get the battery on its own.