Follow these two links for a description of the track and Control modules used in this cabinet.
RFID uses small glass encapsulated 'tags', these contain a transmitter that when energised by a field generated by the 'reader' transmit a unique number which is received by the reader and passed as serial data to a PC. In this demonstration the tags are mounted on various items of stock, when they pass the reader a Powerpoint presentation is caused to display a page appropriate to the item in question.