Charm Necklaces are nonelectrical tracking devices created by Valentin Avellan. After Juni became a spy, Valentin became worried for his safety and sent him a charm necklace with a tracer in for Christmas. Juni never took the charm necklace off since. Valentin wears a similar necklace.
Spy Kids 2
After Carmen and Juni destroy the trackers in their teeth, Valentin uses his charm necklace to find Juni’s location. Later, Valentin tells Juni that if he always takes the necklace with him, he will always be there for Juni.