When activated, all smoke detectors in your home alarm at the same time. Really hard-wired detectors are often on and when the facility goes out, the battery backup kicks in.???? ??????? ????? ?? ??????? ???????? ??? ????? ??? ????? ? ????? ??????? ?????? ??? ????? ????? .?? ?????? ???????? ???? ?????? ??????? ???? ?? ????? ???.Uncomplicated to hol