Also known as a unit crest or DUI, a Distinctive Unit Insignia is worn by all Soldiers (except General Officers) in units that have been
authorized to be issued the device. It is worn centered on the shoulder loops of the Army Green Service Uniform (AGSU) and the blue Army Service Uniform (ASU, Enlisted only) with the base of the insignia toward the outside shoulder seam. DUIs are not worn on the Dress variations of either uniform, however.
For Enlisted personnel, the insignia is centered on a shoulder loop by placing it an equal distance from the outside shoulder seam to the outside edge of the shoulder-loop button. Officers (except Generals) wearing grade insignia on the shoulder loops center the DUI by placing it an equal distance between the inside edge of the grade insignia and the outside edge of the button.
Full guidance on wear of the DUI is found in DA Pamphlet 670-1,
Section 21-22, "Distinctive unit insignia" and 21–3(d) and (e),
"Beret" and
"Garrison Cap," respectively.