temperature sensor for tunnel

NB-IoT heat alarm direct from Wanlin Fire Protection — 12-year factory experience, WL-HD901 fully certified UL 521/EN 54-5/CE/FCC/RoHS/REACH. Key specs: WiFi + Bluetooth 5.2, Fixed Temperature Thermistor + Temperature Compensation, 10-year sealed lithium battery. MOQ 100 units, 25-30 working days, OEM/ODM custom branding available. Serving 60+ countries acro···