An Army unit crest, or distinctive unit insignia, is an enamel patch or metal heraldic device worn by soldiers in particular units of the U.S. Army. All major command operations, field hospitals, logistics and corps groups, and surveillance organizations are authorized to wear their own distinctive unit insignia. The designs are approved by the U.S. Institute of Heraldry and are worn on various parts of the uniform, including the beret flash, the breast patch or the shoulder loops.
After 1965, authorization for distinctive unit insignia was extended to many groups and career organizations that did not have the privilege in earlier years. A full list of authorized units is available in the archives of AR 670-1 as of 2015. Any unit that does not have authorization may request insignia permission if it has at least 500 military personnel.
The design of the insignia is based on the unit's historical record, and the manufacturer takes important decorations, honors, battles and missions into account. Once a distinctive unit insignia is created and approved, it is only changed if a historical error is found as a result of more research. Even if a unit's designation changes, the distinctive unit insignia remains the same as long as its design is factually and historically accurate.