Review on TKSTAR GPS Tracker for Bicycle and Small Vehicles - Hidden Real-time Track, Long Standby, SIM Card GPS GSM GPRS Tracking Devices with LED Tail Light - Lifetime Free Platform (Model: TK906) by Austin Wolf

That's a pretty cool idea. The device charges quickly and the battery lasts a long time in standby mode. I was able to set up SOS and Admin numbers. I can send a message from my SIM card, get a message back with GPS coordinates and click the link to track my bike. When I press the SOS button, I get an SMS with the location. However, I can't get the APM set, so I can't use it with the app. I'm sure I did it right, you send gprs123456 to the sims phone number to enable gprs and the device sends me a text saying "gprs ok". Then send apn123456 and then my carrier's apn and I get the text "apn ok" but apn is still coded as wholesale and won't let me change it to anything else. So I'm glad I have a light and can track my bike but not real time and track my rides.