The Prime 3G GPS Tracker has a Geo-fence feature which will identify and trigger an alarm when the tracker enters or leaves a geographical area drawn by the user within the Tracking Panel. The alarm is displayed on the Tracking Panel and an alert text message can be sent to up to four predefined mobile numbers. Geo-fences are extremely helpful to alert you to the theft or unauthorised removal and use of a vehicle or asset from its normal location. They are also used to help protect vulnerable people; if they leave a Geo-fence zone, you will be notified.