fire door reminder for factory

NB-IoT fire door device supplier direct from Wanlin Fire Protection — 12-year factory experience, WL-FD107 fully certified EN 1155/NFPA 80/CE/FCC/RoHS/REACH. Key specs: Acoustic Trigger + 4G LTE + WiFi, Acoustic/Electromagnetic Retainer + Auto Release, AC 230V or 10-year sealed lithium battery. MOQ 100 units, 25-30 working days, OEM/ODM custom branding avai···