replaceable battery smoke detector

studio loft smoke alarm direct from Wanlin Fire Protection — 12-year factory experience, WL-SM602 4G standalone smoke detector certified CCCF/GB 20517-2006/CE/UL 217/EN 14604. Key specs: Dual Light Path Photoelectric + Electrochemical CO Sensor + 4G Cat.1 Communication, 4G LTE Cat.1 + Cloud Platform + Dual Alarm Channel (Smoke + CO) + SMS/Push/Email. Dual li···