Hacker's ramblings

Everybody who has ever been to a store has seen those electronic gates which are meant to keep shoplifters from stealing stuff. Normal shoplifters use some kind of countermeasures and are actually not bothered by the gates, only honest people get to suffer from them. Typically the gate triggers the alarm by accident when shop personnel simply forgot to remove the tag, or sometimes a rolled wire of some sorts will resemble a coil so that the gate thinks that my recently bought extension cord and/or Ethernet cable is an anti-theft tag. The other not-so-typical scenario is that, there is a tag attached to thing that you bought, but the gate does NOT trigger the alarm. Well, this time that's what happened.

I'm at home and realize, that there is a tag attached. It looks ugly and annoying and should be removed. Since I've always wanted to know how do they remove them in the shop, I took my trustworthy Dremel and started cutting.

Here are the pics:

It looks that there are 4 lightly magnetic ball bearings inside a small cavity made out of plastic and steel. The steely part of the cave is also magnetic so that it attracts the ball bearings to stay on that side. Then there is the part they remove in the store, it is a metallic stud which really doesn't move a lot when pulled. If a lot of force is applied to the stud, the four ball bearings are tightening to the direction of the pull, so that is it impossible (or very very hard) to actually succeed in removing the stud from the tag. In the store (you see them next to the cash register) they have a powerful magnet which is applied to the plastic side of the tag. When the tag is placed on top of the magnet, it pulls the ball bearings down (with the help of gravity), making the stud move away. A removed stud slips back to the tag very easily without magnets or anything, the ball bearings just move out of the way.

The tag is fully covered with plastic and most of it is a coil for the gate. Normal tags don't have sharp edges or brownish dust from dremeling. This one does, since I literally cut it half. The white plastic part in the 2nd pic is typically covered with the black plastic. Also the stud in the pics 3 and 4 is bit longer, since it is not cut short with a power tool.

Next question typically is: How to remove them next time without cutting/breaking the tag? My answer is that I don't know. My tag is busted anyway, but next time I have one that is not busted, I'll try applying some sort of magnet and hitting the tag to the direction of the magned. Eventually, it boils down to the magnetic force, so a powerful one is recommended. I don't know if I have one that has enough pull in it, but I'll sure try. Another thing that comes into mind is to keep twisting the stud while pulling, it should make the ball bearings roll and stay loose enough.