GLENDALE ( —  Four smash-and-grab thieves stole more than 30 Rolex watches from a jewelry store in the Topanga Mall Wednesday.

What the thieves didn’t know was that at least one of the watches had a tracking device.

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CBS2’s Amy Johnson reports that more and more high-end items are coming with GPS devices.

It was a scene that caught shoppers at the Topanga Mall by surprise. Four masked men smashed jewelry cases at Ben Bridge then ran off with dozens of Rolex watches.

“You don’t see cops with shotguns and AR’s and [flak] jackets ,” said shopper Sam Zadeh. “That is what we saw and I was like, ‘Something’s probably happening. Obviously, these things are scary.”

At least one of the watches had a GPS tracking device that led officers to the 405 freeway at Skirball, where the thieves apparently dumped it.

“We’re always looking for ways to hide them,” said Lee Knight of Phantom Tracking. “Like I said, the real weakness is, if it’s removed, it’s pretty much over. So we’re looking for ways to hide them all the time. And obviously the smaller the better.”

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Knight started Phantom Tracking in 2005 after a friend’s motorcycle was stolen. Now his business has expanded into theft deterrence and monitoring of just about anything.

“We’ve tracked things as far as Tajikistan and Beijing,” Knight says.

Detectives and Ben Bridge both declined to comment about GPS trackers and the robbery, but Knight told Johnson how well they can work.

“It can help calculate multiple locations,” he said, “and it can calculate up to 12 satellites at once. To a very precise location — within 3 meters anywhere on the globe.”

The smallest GPS tracker currently available is about half the size of a dime, but a new one — out this fall– will be two-thirds that size. With the advances in technology, they’ll continue to get smaller and do more.

“There are applications everywhere. Putting them on Alzheimer’s (patients), putting them in kids’ backpacks. One company is actually building the GPS into the kids’ shoes.”

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He says the toughest part is hiding the GPS trackers from thieves.