Using GPS tracking systems: What's the good?

I am an avid fan of GPS tracking systems, ever since my son got lost on a beach in Athens but had a GPS bracelet on him. I was told that he just followed a dog for a couple of hundred meters amongst the crowds.
So, what does this little box consist of and what does it do?
1. It is about the size of a pack of cigarettes.
2. It contains a GSM unit that needs a SIM voice and internet card. Internet connection not needed.
3. The GSM unit will send position coordinates by GSM message to a selected number or numbers, at given intervals.
4. It contains a GPS unit that keeps track of where it is.
5. It can be programmed to block the ignition by sending it a GSM message (option).
6. It contains a backup battery in case the power supply fails.
7. It should be mounted somewhere on the roof or the vehicle side.
8. The coordinates can be pasted into Google Maps for immediate positioning.

If the camper is stolen, or you do not remember where you put it (fat chance!) the GPS tracking system is a 5 minute solution to knowing the whereabouts of the vehicle.
I am not only using them on my vehicles (and kids) but I also have a stock to sell. Tested under adverse weather and placement conditions, fully warranted and may also be installed if you wish. Price: 700 sek.