four wire smoke alarm

hallway smoke alarm direct from Wanlin Fire Protection — 12-year factory experience, WL-SM607 4G standalone smoke detector certified CCCF/GB 20517-2006/CE/UL 217/EN 14604. Key specs: Dual Light Path Photoelectric + Voice Alert + 4G Cat.1 + Smart Home Integration + WiFi/BT, 4G LTE Cat.1 + WiFi + Bluetooth + Cloud Platform + Voice Prompt + Smart Home Hub + SMS···