A distinctive unit insignia (DUI) is a metal heraldic device worn by soldiers in the United States Army. The DUI design is derived from the coat of arms authorized for a unit. DUIs may also be called "distinctive insignia" (DI), a "crest" or a "unit crest" by soldiers or collectors. The term "crest" however, in addition to being incorrect, may be misleading, as a DUI is an insignia in its own right rather than a heraldic crest. The term "crest" properly refers to the portion of an achievement of arms which stands atop the helmet over the shield of arms. (Nevertheless, a minority of DUIs happen to depict crests, such as those of many National Guard state area commands.) The U.S. Army Institute of Heraldry is responsible for the design, development and authorization of all DUIs.