GF21 Mini GPS Tracker

This gps tracker can not work if a sim card is not inserted. it can work with or without the mobile app, so you can have real-time tracking either using sms or the mobile app available for android and ios. only gsm sim card works in this model. gps locator please make sure gsm sim card supports making calls, sending messages, gprs network. specifications: network: gps/agps/lbs/wifi battery type: 3.7v 600ma li-ion battery charging voltage: dc 5v frequency: 850/900/1800/1900mhz charging input: ac 110-220v 50/60hz gps positioning accuracy: about 10m standby time: 10 days work time: 4-6 days expansion card: mini sim card (not included) color: black material: plastic