The Roost Smart Smoke Alarm is a logical step forward for the company that made the.
The battery is a useful, Wi-Fi-connected 9-volt that fits in your existing alarms and sends push notifications to your phone when the alarm sounds or the battery runs low. The problem with the Roost Smart Smoke Alarm is that it adds nothing to connected smoke detection that the included Roost Smart Battery can't do on its own.
Roost just put its name on a Universal Security Instruments (USI) alarm and called it smart. It's not.
If you do need a new alarm, Roost actually has two options. We tested the $80 RSA-400, which senses smoke, fire, carbon monoxide and natural gas. You can also get the $60 version of the Roost Smart Smoke Alarm -- the RSA-200 -- which just senses smoke and fire. The RSA-400 is reasonably priced. A similar USI smoke and CO detector costs $50, plus the $35 Roost. The RSA-200 is less so, as a USI detector that just smells smoke is only $12.
Either way, I don't recommend replacing a working smoke alarm with a Roost Smart Smoke Alarm just to add remote notifications. You can get that with a $35 Roost Battery and your existing alarm. If you want wholesale smart replacements, I recommend spending a little more for the $100.
I really liked the Roost Smart Battery when I reviewed it last year. It looks just like an ordinary 9V, so if you can replace a battery, you can install a Roost. Hidden in that familiar form are a Wi-Fi antenna, a microphone and a replaceable power pack that snaps free from the bottom of the battery. Supposedly, a Roost lasts five years. When that time expires, you'll get a notification and you can buy a new power pack for $15.
The Roost App is simple and intuitive. Alerts arrived promptly when we tested it. Now, the Roost works with online rule maker IFTTT so it can integrate with a larger smart-home setup. For example, you can create a recipe that tells your smart lights to flash when your alarm sounds.
Because of how much I liked the Roost battery, I had lofty expectations for the Roost Smart Smoke Alarm. One criticism I had of the battery is that the in-app silencing feature doesn't work on hard-wired alarms. That's understandable, as it's just a battery and it silences the alarm by cutting the power. I thought the Roost Smoke Alarm would certainly address this problem, as well as close the gap between the Roost Battery and Nest in other ways by adding a light, a motion sensor or the ability to talk to other smoke detectors. Nope, nope and nope. The Roost Smoke Alarm adds nothing. In fact, Roost's Smart Battery would be more useful in a different, battery-powered -- app-silenceable -- smoke detector.