Frocking customs and policies vary across military services, particularly for enlisted members. In the United States Army a general officer may request authority to frock soldiers of his command. In the United States Air Force, only senior field grade and general officers are usually frocked. The United States Navy makes use of frocking much more frequently than do the Army and the Air Force. An example of this is when all new chief petty officers of the United States Navy are frocked on September 16 of each year, although their official date of rank will be at different times over the next year.