Do not buy it, it is not worth it, it is worse than a cheap one. I installed four and have already changed two because they kept whistling for no reason and could be heard throughout the whole block. They turned out to be completely faulty and the company does not accept returns, only repairs, which do not come back even after a long time. Because these are rentals, at first I was forced to change one with another from the same company, and again the same issues for no reason—just when the sun comes out, it starts up and whistles.

I bought 2 detectors in March but I installed them a week ago when I went to an island, in 2 rooms. From the beginning, the alarm was going off for no reason and I had to press the test button on it; it would stop for a while and then the alarm would go off again. Eventually, one of them stopped working and I removed the batteries from the other one.
I contacted the store that sent them on May 28th and I am still waiting for the technician to call me

It is not a sensitive sensor and does not prevent dangerous situations. It simply confirms the presence of smoke when the entire area is already filled with smoke. Update: after two years it still works with the same batteries. Three times when needed, it functioned normally and the noise wakes up the whole neighborhood. VFM!!!