Insteon Wireless Hidden Door Sensor, Automatically Turns On/Off Lights, Use with Insteon Hub for Smartphone Alerts, Uses Mesh Wireless Technology, Ultra Reliable, Better than Wi-Fi, Zigbee & Z-Wave Automatically control lights and appliances when doors open and close Wireless up to 150 feet Battery-operated, no wires or professional installation required Long-lasting contact plunger ensures reliable operation for years and years Flush collar with retention screw for a clean, secure mount