for officers of the rank of wing commander and below Black and polished with one row of gold oak leaves for officers of the rank of group captain Black and polished with two rows of gold oak leaves for officers of the rank of air commodore and above The caps of other ranks of the RAF Police have a white crown. Officer cadets wear the officers' cap with a white band instead of a black band. Female officers and warrant officers wear a peaked cap of a different pattern. Female other ranks wear a round hat instead, although the female version of the peaked cap was formerly worn by all female ranks of the RAF Police. For uniformity, however, female musicians wear the same peaked cap as male personnel in formal dress. All ranks of the Women's Auxiliary Air Force wore a peaked cap of a different pattern again, similar to that of the Auxiliary Territorial Service. United States United States Air Force In the United States Air Force, all personnel have the option to wear service caps, but only field-grade (major through colonel) and general officers are required to own one. The service cap is issued without charge to enlisted airmen assigned to certain ceremonial units and details. Air Force service caps are Air Force blue (shade 1620), matching the coat and trousers of the service dress uniform, with a gloss black visor and black chinstrap secured by silver-colored buttons bearing a version of the "Hap Arnold emblem" first designed by James T. Rawls for use by the Air Force's predecessor, the Army Air Forces, in 1942. The cap badge consists of a relief of the Great Seal of the United States rendered in silver-colored metal. For enlisted members, the arms are surrounded by a silver-colored metal circle. Commissioned officers' insignia is larger and lacks the encompassing circle. The Air Force Band and Air Force Base Honor Guard each have their own distinctive cap insignia and other uniform devices. Field-grade officers' visors have two pairs of clouds and lightning bolts, patterned after the oak leaf motifs used by the other services. General officers' caps add an extra pair of clouds and bolts on the visor, while the cap of the Chief of Staff of the United States Air Force adds clouds and bolts around the entire cap band. The clouds and bolts are jokingly referred to in military slang