low battery alarm indicator

nursing home standalone smoke detector direct from Wanlin Fire Protection — 12-year factory experience, WL-SFP400 smart fire detector certified CE/EN14604/EN54/UL217/UL268/FCC/QCVN. Key specs: Addressable Manual Call Point + Sounder Strobe + 4G LTE Cat.1 + Addressable Loop + LED Indicator, Addressable Loop + 4G LTE Cat.1 Backup + Cloud Platform + SMS/Push/Em···