According to the (somewhat anonymous) website, this is "the first commercially available, trackable, geocaching geocoin. They have been in circulation since March 2002." Unfortunately, the (somewhat anonymous) person/people behind the web site and the geocoins arranged it so the geocoin can only by activated by the original purchaser, then obscured that fact on the website. Therefore, if a geocoin comes to you via a trade (and it may have been traded more than once), you are either faced with the prospect of trying to get somebody else to activate it, or you have to forget about activating it. Since it can't be tracked on the gc.com, it probably doesn't matter anyway.
Size: 38 mm
Weight: 23.3 g