Roost RSA 400 Smoke/Fire/CO/Natural Gas Alarm was created to make the best use of the Roost Smart Battery, a device born from a crowd funded project similarly to Halo, but, this time, using Kickstarter and because of its unique abilities, it quickly became a very popular product. The Roost Smart Battery is equipped with a WiFi adapter, a microphone and, if used with an already existing smoke alarm, it can bring a new array of functions for an increased level of convenience and to make your home a lot safer after it gets connected to your home WiFi network, you get notifications in case of emergencies, when the battery is running low, allows snoozing in case of false alarms this feature did not work with hard wired alarms and an easy to use app to monitor your device. The Roost RSA 400 takes things further and, besides delivering every function of the Roost Smart Battery, it detects the usual trio: smoke, CO and fire and, additionally, it can also sense the presence of natural gas a unique addition for this type of detector. Even if the Roost RSA 400 could fit among the smart detectors, when compared with Halo Smoke Alarm, Onelink or Nest Protect, its design is pretty unremarkable. So, similarly to the traditional smoke detectors, the case of the Roost RSA 400 is circular, while towards the bottom, the body gets narrower and finishes into a larger, thin plate where the device gets in contact with the ceiling or wall. Since the plastic case is covered by a white matte finish, it will easily blend in on a ceiling it actually looks like a flush mount lighting and, since it is a relatively small device it measures 5. 63 x 5. 63 x 1. 75 inches, it won’t attract too much attention. On the top of the detector, there is a recessed zone on which resides an elevated button press to silence the CO/smoke alarm and hold it to test weekly, a CO/GAS indicator, a Power/Smoke indicator and four circular cut outs for the speaker. There are no other flashy design elements, such as a large LED light, so compared with other ‘smarter’ detectors, it may look a bit plain, but it does have everything one would expect from a smoke/CO/gas/fire alarm.