This geocaching trackable geocoin is to recognize a geocaching milestone - the completion of an 81Grid! Some people call this a geocaching fizzy grid instead of 81 grid. By either name, a geocaching fizzy grid or geocaching 81 grid, it is the same great geocaching achievement!
The coin is 45mm x 45mm (1 3/4" x 1 3/4"), 3.0mm thickness and plated in polished nickel. There is a combination of solid and translucent IHE paint.
There is a custom icon on geocaching.com of course.