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