Features: Setting up a geofence for the tracker to restrict its movements within a district. The GPS locator will send alarm information to APP or send a message to the authorized number when it goes out of or get in this district. Fence: Designate an area on the map by setting the device as the center-point and the alarm will be triggered off immediately once the user of the device goes into or out of this area. In for case-of emergency-, press the SOS button and the device will send out the call and message for help to the guardian-. Find Device: The lost device can be found through the APP on the cell phoneVoice: With the highly sensitive microphone, the sound around the device can be heard in real for time in for case-the emergency- happens to the user. Support: real-time GPS/AGPS/WIFI/4G Cat 1/GSM positioning, SOS for help, calling a family number, electronic fence warning and reminder, historical track query, and power saving mode. Specifications: Material:ABS Size:Approx.6.3x3.6x2.75cm/2.48x1.41x1.08inch Size:Approx.8.45x4.5x3.15cm/3.32x1.77x1.24inch Size:Approx.10x5.8x3.16cm/3.93x2.28x1.24inch Model S:3000mah Model M:6000mah Model L:10000mah Package Includes: 1x GPS Tracker note: 1.Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. 2.Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thanks for your understandings.