What is the button on the magnetic side of YoGPS magnetic GPS Tracker?

The button on the magnetic side of the YoGPS Magnetic GPS Tracker is used for tamper alert. When the tracker is placed in a vehicle on its magnetic side, the button is pressed. If someone tampers with the GPS device, the button is released which triggers a tamper alert to your phone. Keep track of your vehicle and belongings with this reliable and secure GPS tracker.