This is an industrial-grade magnetic door lock sensor. Consists of a Magnet and a Magnetic Sensor(the one with three wires). The sensor has a simple switch within it which gets activated in the presence of a magnet. To use the sensor as a door/window lock sensor, mount the magnet on the door/window and the magnet sensor on the door/window frame. When they are separated, the magnet sensor detects that the door/window is opened. This sensor can be used with other commonly available magnets also.
NOTE: When the switch is in contact with the sensor it is closed, when the switch is not in contact with the sensor it is open.
Example: This magnet sensor can be used on doors, When the door is open, the Magnet sensor is open and when the door is closed the Magnet sensor is closed.
1 x Door Lock Sensor Industrial Grade (Normally Open, Normally Closed, 3 Terminal)