To mount the product on the ceiling, also white plastic ring is first screwed to the ceiling. Therein, the device is screwed in, and when it is locked, then also automatically set alarm.
To the beat of each 53 seconds, a red LED flashes on the fact that signals that it is ready for use. Should the battery at some time to go to the end, the same LED flashes frequently and beeps. According to the manufacturer, however, this should only be the case in about 10 years. As long as the built-battery lasts namely. Then you have to replace the unit completely, respectively, carry out the waste. Under normal smoke detectors you have to check the battery, or replace about once a year. Hence the slightly higher price makes then paid again.
Unfortunately the device is only an English manual. Although there is not really much to explain, yet older people without knowledge of English so have their problems, especially with regard to the different sites and their features. Therefore, a star deduction. The device itself is impeccable.
