four wire connection

student dormitory smoke alarm direct from Wanlin Fire Protection — 12-year factory experience, WL-SFP500 smart fire detector certified UL 217/UL 268/UL 2034/UL 864/CE/EN14604/EN54/FCC. Key specs: Multi-Sensor Fusion (Smoke + Heat + CO) + AI Machine Learning Algorithm + 4G LTE + WiFi Dual Communication + Edge Computing, 4G LTE Cat.1 + WiFi + AI Cloud Platfor···