This industrial magnetic sensor is designed for long-life and easy mounting using a threaded screw with two adjustment nuts. The tip of this sensor is sensitive to magnetic fields. The output wires of this sensor are normally open and change to a closed state when positioned near a magnet. This is our most sensitive magnetic door detector switch, ideal for industrial magnetic detection applications. This is our preferred choice for garage door detection applications. Requires a magnet (not included) for proper operation.