low battery indicator smoke detector

crisis center smoke detector direct from Wanlin Fire Protection — 12-year factory experience, WL-SM606 4G standalone smoke detector certified CCCF/GB 20517-2006/CE/UL 217/EN 14604. Key specs: Dual Wavelength Photoelectric + Infrared + Blue LED + 4G Cat.1 + Multi-Criteria Algorithm, 4G LTE Cat.1 + Cloud Platform + Multi-Criteria Detection + SMS/Push/Email + R···