The cable looks like the normal USB to dock connector cable that comes with every iPad, iPhone, or iPod touch; however, it has a tiny lock logo on its front.
When attached to an iDevice, the cable physically locks in to the product's metal chassis just as a normal dock connector, but the internals have been tweaked to prevent the unit from disengaging, essentially tethering the product to the display table. While the inner workings of the new cable are a mystery, a simple reshaping and bolstering of the attachment prongs could easily do the job, much like the first-generation 30-pin connectors that could only be released when users pinched two side-mounted actuators. It is thought a special tool may be needed to disengage the unit, though representatives declined to comment on the mechanism's intricacies. Also unknown is how the USB side of the cable works with the system as it was hidden within the display table, but it is most likely attached via conventional means.
Previously, Apple used a security system that involved a thin wire affixed to the back of the device using a strong adhesive. The new cables look much better and are reportedly alarm capable; however, it's unclear how the exactly the alarm function works.