On 08/09/2016 18:45, ARW wrote:
I know that it is a 30mm by 4mm glass capusle with some electronics
inside it.

But other than that I have no idea.

http://wiki.diyfaq.org.uk/images/2/2f/Wtf1.jpg



It's an RFID transponder. Coil is energised by a near-field device,
transponder sends it's ID to the energiser. Usually contained inside
something like this :

http://www.rexson.co.uk/images/reasons/8_480x268.jpg