If you want to shell out some serious coin during the next promotional campaign, these zinc Challenge coins will do the trick! They 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