In the United States Navy, midshipmen, chief petty officers, and commissioned officers wear combination covers, but there are differences between the three types. Midshipmen at the United States Naval Academy, United States Merchant Marine Academy or in Naval Reserve Officers Training Corps (NROTC) units wear a combination cap with a gold chinstrap attached by gold buttons, with a gold fouled anchor device. A chief petty officer wears a combination cap with a black chinstrap attached with gold buttons, with a device consisting of a gold fouled anchor with silver block letters "USN" superimposed on the shank of the anchor, with the addition of one, two, or three stars at the top of the anchor if the wearer is a Senior Chief Petty Officer, a Master Chief Petty Officer, or the Master Chief Petty Officer of the Navy, respectively; while a commissioned officer wears a combination cap with a gold chinstrap attached by gold buttons, with an officer crest device, a silver federal shield over two crossed gold fouled anchors, surmounted by a silver eagle. Chief petty officer and junior commissioned officer visors are shiny black plastic without ornamentation. Officers O-5 (Commander) and above have gold embroidered oak leaves and acorns on a black felt-covered visor, with additional embroidery for flag officers (O-7, or rear admiral lower half, and above), referred to as "scrambled eggs." A thin plastic crown and metal hoop provides structure, and the covering fabric come in khaki or in white (since 1963, the white combination cap is worn with both white and blue uniforms). The black band around the cap includes a black circle extending upward on the front of the crown as a backing behind the device. The gold buttons on the sides of the cover that fasten the chin strap are of a design to match the gold buttons on the service dress jacket and the snaps on officer shoulder boards. For the former female cap the brim was folded up on both sides whereas the men's cap has no brim but a visor at the front; the female cap was discontinued October 2018.