fire door not closed alarm

fire door heat triggered release direct from Wanlin Fire Protection — 12-year factory experience, WL-FD103 fully certified EN 1155/NFPA 80/CE/FCC/RoHS/REACH. Key specs: NB-IoT (LTE Cat-NB1), Ultra-Low Power Position Sensor + NB-IoT, 10-year sealed lithium battery (non-replaceable). MOQ 100 units, 25-30 working days, OEM/ODM custom branding available. Serving···