Security: door and window magnetic inductor, rolling door in place detection Liquid level detection: float liquid level switch (water heater, water tank, chemical liquid) Home appliances: washing machine door switch, coffee machine water level, refrigerator door control light High voltage instrument: withstand voltage tester, insulation resistance tester, high voltage signal acquisition Industrial equipment: cylinder magnetic switch, equipment limit, explosion-proof detection (without electric spark) Electronic water/gas meter: passive counting, ultra-low power consumption