Over the years, many military traditions have originated and evolved to show one's camaraderie, the most notable being a simple coin! A coin with symbols that reflect a person's service and loyalty to a widespread organization. Such coins are called challenge coins, and they’ve traveled far beyond the reach of the military to the loyalty of regular civilians.
Challenge coins tend to be quite small. Their diameter varies from 3.8 centimeters to 5 centimeters, and the thickness is about 1/4 of a centimeter. Though most of the coins are circular, some come in all sorts of shapes — pentagons, dog tags, shields, and even arrowheads. Their composition generally includes copper, pewter, and nickel, but many other finishes are often used. Some designs can be simple — just a small emblem or symbol, — but others can have intricate cut-outs, complex designs, and even 3D parts.