Mighty Mule Reliable and Supreme Accuracy Wireless Home Driveway Sensor Alarm Systems with 2 Base Stations Features: With a simple installation of burying the Electromagnetic Sensor Wand by it next to your driveway, and detects mass metal moving within a 3-12 ft. radius of the wand. When a vehicle passes by the sensor, an outdoor transmitter communicates wirelessly to an internal base station up to 400 ft. away and sounds a pleasant chime The outdoor electromagnetic sensor only detects vehicles; no false alarms due to animals, children, etc. Ideal for residential and commercial properties.