Keruve pitches their people tracker for Alzheimer’s patients… but it seems better suited for many other spy related uses. The unit works on GPS and cell tower’s (if GPS isn’t available, know as A-GPS) to locate your target. If you are going to be attaching the waterproof bracelet (instead of hiding in your targets car or bag) it can be secured so that you need a tool (or scissors) to remove it. The unit will set you back about $1,400.