polarity insensitive connection

sustainable smoke alarm direct from Wanlin Fire Protection — 12-year factory experience, WL-SFP600 smart fire detector certified CE/EN14604/EN54/UL217/UL268/FCC. Key specs: Fixed Temperature + Rate-of-Rise Heat Sensing + LoRaWAN Long Range + Ultra-Low Power + Dual Communication, LoRaWAN + IoT Gateway + Cloud Platform + Long Range (up to 15km) + 4G Cat.1 Bac···