Outstanding collector's items, these 2.25" zinc challenge coins rival in quality to our brass coins at a lighter weight! Originating during World War I, Challenge coins were issued to battalions as symbols of camaraderie and unity, and later they were used as a way of verifying membership in clubs, groups and military units. They are now commonly given away at military and DOD meetings as a token of appreciation. Create a memorable keepsake by adding a customized imprint of your choosing