continuously adjustable volume

4G LTE cellular communication direct from Wanlin Fire Protection — 12-year factory experience, WL-SFP700 smart fire detector certified UL 217/UL 268/UL 2034/UL 864/CE/EN14604/EN54/FCC. Key specs: ARM Cortex-A7 Processor + 4G LTE Cat.1 + WiFi + Ethernet + Zigbee + Bluetooth + Cloud Platform Integration, 4G LTE Cat.1 + WiFi + Ethernet + Zigbee + Bluetooth + Io···