I don't use any GPS tracking, but he's either with me, at home or in school - otherwise with my parents when I'm busy. Don't really know a lot about available tracking devices, but just a word of caution that if someone manages to hack into the company's system, they can track you by your account (which has personal info like email, contact etc) and also the GPS route of where, when and how often your child goes so ... I'd say it's quite dangerous? As an adult, I close my own GPS on my phone for that same reason too. Another alternative to such security measure would be to keep a small booklet/slip of paper with your child's information like name, age, height, weight, any special things you can specifically identify your child with (eg. black birthmark on left arm), recent photo (against any standard sized object for comparison) as well as samples of their DNA from nail clippings and hair pluckings (pluck directly from the root, not cut) and their fingerprints (all 10 fingers, labelled). It's not the best, but it does help if there's ever an emergency of your child going missing because the police can use them to help find your child - make sure to update it regularly!