We are a professional gps tracker manufacturer with top quality and much more competitive price.Pls also allow me to briefly introduce our trackers 1)Our trackers are good quality with competitive price,We test each tracker one by one before shipment 2)Our trackers are easy to use and Our tracking platform is free and perfect,But others need year fees 3)We have long time warranty and We offer free maintenance on the condition that the freight fees paid by buyers 4)Our trackers have passed CE/FCC Certificates 5)We have our own powerful engineers who can give technical supports at any time 6)We also offer sample order to test our trackers 7)Our engineers have already added GSM Positioning on our 900C,900E trackers,When at the blind area or the GPS cannot receive signal,for example,Tunnel or internal parking place,The Tracker will switch to GSM Positioning automatically.Then GSM Positioning has played a accessorial role for GPS Positioning.