Final answer:
The cap device for commissioned warrant officers is an insignia on the headgear indicating rank and branch, typically featuring symbolic elements such as a silver eagle and a gold fouled anchor, varying by country and service.
Step-by-step explanation:
The cap device for commissioned warrant officers in military uniform refers to the insignia worn on the headgear that signifies their rank and branch of service. Although the exact design can vary by country and service branch, typically, for example, in the United States Navy, a commissioned warrant officer's cap device features a silver eagle rising from a gold fouled anchor. The placement and manner of wear of the cap device are outlined in uniform regulations, which commissioned warrant officers are expected to adhere to as part of maintaining proper military bearing and appearance.