In addition to basic uniform clothing, various badges are used by the USAF to indicate a billet assignment or qualification-level for a given assignment. Badges can also be used as merit-based or service-based awards. Over time, various badges have been discontinued and are no longer distributed. Authorized badges include the Shields of USAF Fire Protection, and Security Forces, and the Missile Badge (or "pocket rocket"), which is earned after working in a missile system maintenance or missile operations capacity for at least one year.