Back in April of this year, Nest stopped selling the Protect smoke alarm after an issue surfaced with the wave feature. The wave feature was designed to allow the user to silence the alarm and that feature was malfunctioning leading to Nest issuing a patch that disabled it on units in use.
Nest has now announced that the Protect is available for purchase again. However, the wave feature is still disabled on the Protect. An investigation into a solution for the wave issue is underway. The Nest Protect is designed to alert a smartphone if smoke is detected so you can keep an eye on your home or office from afar.
The Protect can also monitor levels of carbon monoxide. Nest is selling the Protect for $99 right now; its original launch price was $119.