These 2.75" brass Challenge coins are collector's items that are bound to be cherished for a lifetime! 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. Customize imprint of your brand logo or message to make these mementos your own.