What did Lord Sauron, when forging the One Ring in the fires of Mount Doom forget to include in his all powerful ring? What did he forget to leave out of the ring impervious even to dragon fire, designed to rule over all free peoples of Middle Earth in perpetuity - a ring destined to be the One Ring to Rule Them All, to tempt its wearer with the promise of infinite power? Thats easy - it could have used an embedded RFID/NFC transponder!
NFC (near field communication) technology is a great way to interact wirelessly with projects. With the RFID/NFC Smart Ring your ring can communicate with your smart phone/tablet, computer, or much more! Contains two MiFare Ultralight C - NTAG 213's with 144 bytes of read/write memory. One is on the 'inside' of the ring towards the palm, the other is underneath the jewel. You can use tags to launch apps, unlock your phone, transmit a URL, control an Arduino, etc.
This is RFID/RFID Smart Ring with a 20mm Inner Diameter. We have a bunch of sizes in the store!
NFC is a way for two devices very close to each other to communicate. Sort of like a very short range bluetooth that doesn't require authentication. It is an extension of RFID, so anything you can do with RFID you can do with NFC. Because it can read and write tags, you can always just use this for RFID-tag projects. This ring can be read by any NFC/RFID reader with ISO 14443-3A MiFare Ultralight/NTAG support (which is pretty much all of them), including our PN532 readers and various tablets and phones.
Learn more about RFID / NFC products and projects on the Adafruit Learning System.