Embroidered shoulder epaulet rank worn by Non-Commissioned Officers, Warrant Officers and Officers on the Army Service Uniform shirt shoulder loops. Sold in pairs. Small rank marks are typically worn by females and large are typically worn by males, but sizes are not exclusive to male or female and may be worn by either, as long as they fit the shoulder loops on the garment.
Junior enlisted (Private Second Class, Private First Class, and Specialist) do not wear rank shoulder marks. They instead wear brass rank insignia on the collar tabs.
From the DA PAM 670-1 21-6 regarding placement of the Rank Shoulder Mark Insignia:
(4) Sizes. Shoulder marks come in two sizes to accommodate differences in the manufacturing of shoulder loops on shirts and sweaters. All personnel may wear either size of the shoulder marks. The shoulder mark fits the shoulder loop properly when the hook-and-loop attachments or buttons are completely exposed, enabling exact alignment of the hook-and-loop attachments or fastening of buttons.
(a) Male (large). The large shoulder mark is 2–1/8 inches wide at the base and 4–1/4 inches long, tapering to 1–3/4 inches wide at the top.
(b) Female (small). The small shoulder mark is 2–1/8 inches wide at the base and 3–1/4 inches long, tapering to 1–25/32 inches wide at the top.
(5) How worn. Shoulder marks are worn by all personnel in the rank of corporal and above on the shoulder loops of the ASU shirts, the ASU maternity shirt, the black cardigan, and the black pullover. NCOs wear shoulder marks on the all-weather coat and the windbreaker. When the maternity tunic is worn, pregnant Soldiers will button the shoulder loop of the maternity shirt over the top of the tunic shoulder piece so the shoulder mark is visible.