This GPS tracker is around the same size as small mobile phone and uses GPS technology with an accuracy of 10 metres.

Like the G-Sat, it can be used in conjunction with a SIM card, enabling you to make one 'panic' call to a person of your choice. They can track you online using FollowGB's pay-as-you-go web mapping software. It also works internationally - so you needn't get 'lost' when going abroad. Like the Zoombak it also includes alert area SMS texting.

You get 50 free 'tracks' or searches when you buy the product. Additional 'tracks' cost between 5p and 40p depending on tariff.

Safety first?

While we can all think of examples why personal tracking is great idea - the Madeleine McCann case for one, relatives with Alzheimer's Disease another - is also raises a lot of ethical and personal privacy issues.

The biggest of these is that such devices may offer a false sense of security. You may think you know where you kids, car, dog are, but what if they've lost the device, or had it deliberately removed from them. GPS and mobile phone trackers also suffer from a common problem - it may be easy to keep tabs on someone while they're out in the open, but what happens if they go inside a building? Chances are you'll lose the signal.

The other worry, raised by the Privacy International pressure group, is that it may make anxious parents even more protective of their children, so damaging their relationship.

In April 2006, Privacy International director Simon Davis told the BBC:

"There is, particularly for young teenagers, a very important space that needs to be nurtured, for the development of the adolescent psyche. Parents have to be careful not to intrude too closely on that neutral zone."

Davis also warned then that hacking personal tracking devices was also very easy, enabling someone with evil intent to also keep tabs on your children.

Claude Knights, Director of child protection charity Kidscape, told TechRadar:

"Kidscape would be very supportive of any effort to protect children. But just because you've invested a lot of time and money into equipping your child with this it shouldn't lead to you to putting your own radar down. Other forms of vigilance are required.

"One of the things [we're concerned about] is that the technology could have a glitch in it and, if that very day your child is at risk, it doesn't work.

[Protecting your child] should be about your own internal wiring as well - knowing what the safe things are to do, what is not safe, trust between parents and children. All of these things have always been true."