# Tattle Tapes (those little metal anti-shoplifting thingies)
**URL:** https://boards.straightdope.com/t/tattle-tapes-those-little-metal-anti-shoplifting-thingies/36124
**Category:** Factual Questions
**Created:** [October 8, 2000, 5:02am UTC](https://boards.straightdope.com/t/tattle-tapes-those-little-metal-anti-shoplifting-thingies/36124 "2000-10-08T05:02:46Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Inky\_1](https://boards.straightdope.com/u/Inky_1)
#### Post date: [October 8, 2000, 5:02am UTC](https://boards.straightdope.com/t/tattle-tapes-those-little-metal-anti-shoplifting-thingies/36124/1 "2000-10-08T05:02:46Z")
Tattle Tapes. In library book bindings and glued to CD’s, in expensive razor blade boxes and stuck to your knees (well, maybe not, couldn’t think of anything that rhymes with CD’s).
Anyway, anybody know what the scientific principals behind these thingies is? I suspect it’s something magnetic involving those Star Trek sensor gates at the doors, but in that case why wouldn’t they screw up watches and pacemakers and stuff?
Anybody got the scoop? I promise it’s purely curiosity.
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### Author:  [@Alphagene](https://boards.straightdope.com/u/Alphagene)
#### Post date: [October 8, 2000, 5:24am UTC](https://boards.straightdope.com/t/tattle-tapes-those-little-metal-anti-shoplifting-thingies/36124/2 "2000-10-08T05:24:07Z")
Does this help?
From “[How Do Radio Frequency EAS Systems Work?](http://www.howstuffworks.com/anti-shoplifting-device3.htm)”
> [@](#):
>
> A label – basically a miniature, disposable electronic circuit and antenna – attached to a product responds to a specific frequency emitted by a transmitter antenna (usually one pedestal of the entry/exit gate). The response from the label is then picked up by an adjacent receiver antenna (the other pedestal). This processes the label response signal and will trigger an alarm when it matches specific criteria.
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### Author:  [@RM\_Mentock](https://boards.straightdope.com/u/RM_Mentock)
#### Post date: [October 8, 2000, 1:24pm UTC](https://boards.straightdope.com/t/tattle-tapes-those-little-metal-anti-shoplifting-thingies/36124/3 "2000-10-08T13:24:24Z")
That looks like a great site, Alphagene, but I think the OP was talking about the [EM system](http://www.howstuffworks.com/anti-shoplifting-device4.htm) From its explanation at that site:
> [@](#):
>
> used by many retail chain stores, supermarkets and libraries around the world. In this technology, a magnetic, iron-containing strip with an adhesive layer is attached to the merchandise. This strip is not removed at checkout – it’s simply deactivated by a scanner that uses a specific highly intense magnetic field.
I was just about to go looking for a site such as this, to explain those EM systems. Thanks!