Earlier quoted context omitted.
The local Gold's Gym has a theft prevention style detector around the front door which will complain if you try and leave with a towel. The towels themselves have an obvious bump in one corner, about the size of a jellybean.
And they are using NFC for that?
NFC is a specific kind of RFID which uses the ISO 18000-3 band for communication over short distances. There are many other types of RFID, which can have much longer ranges.