Similarly to the Nest Protect 2nd Generation, the Safe and Sound also has a NightLight which can be adjusted in terms of intensity or colour depending on the time of day, but it cannot be set to turn on only during the night while Nest does allow it. The Onelink Safe and Sound alarm is slightly larger than your average non smart smoke detector it measures 6. 8 x 6. 8 x 2. 26 inches and weighs 1. 5 lbs, but, because of its flush mount aspect it does give some aesthetic value to the room. The main attraction is the speaker, which is located on the small middle section which will work in most cases along with the LED ring for example, when using Alexa, the LED will be solid blue when Alexa is processing your request and will become half red when the microphone is muted. I can’t really say that the speaker is among the best, but the fact that you position the device on the ceiling definitely makes it sound better than the regular Alexa devices. The Onelink Safe and Sound is a wired smoke and CO detector a battery only variant for has not yet been released, so, it is advisable that the installation should be conducted by a professional. If you decide to go at it by yourself, these are the steps you need to take: first, you need to make sure not to mount the device in locations where the temperature is either below 40ºF or above 100ºF and the humidity is within the 20 to 80 % range non condensing; secondly, try to avoid spaces where the air is not circulating properly such as in the corners of the room – you can mount in on the wall or on the ceiling and also keep at least 20 feet from any cooking appliance the main source of false alarms. The most common types of smoke detectors are those that are equipped with either a ionization sensor or with a photoelectric sensor or, of course, both.