This is an interesting demonstration project: a hand-held device that disables passive RFID tags.
There are several ways to deactivate RFID-Tags. One that might be offered by the industries are RFID-deactivators, which will send the RFID-Tag to sleep. A problem with this method is, that it is not permanent, the RFID-Tag can be reactivated (probably without your knowledge). Several ways of permanently deactivating RFID-Tags are know, e.g. cutting off the antenna from the actual microchip or overloading and literally frying the RFID-Tag by placing it in a common microwave-oven for even very short periods of time. Unfortunately both methods aren’t suitable for the destruction of RFID-Tags in clothes: cutting off the antenna would require to damage the piece of cloth, while frying the chips is likely to cause a short but potent flame, which would damage most textiles or even set them on fire.
The RFID-Zapper solves this dilemma. Basically it copies the mircowave-oven-method, but in a much smaller scale. It generates a strong electromagnetic field with a coil, which should be placed as near to the target-RFID-Tag as possible. The RFID-Tag then will recive a strong shock of energy comparable with an EMP and some part of it will blow, most likely the capacitator, thus deactivating the chip forever.
An obvious application would be to disable the RFID chip on your passport, but this kind of thing will probably be more popular with professional shoplifters.