United States Air Force Security Forces Colorized, 24K Gold Challenge Bar $15.00 each. This is a great looking United States Air Force Security Forces Commemorative Challenge Bar that is a uniquely shaped rectangular bar that measures 1” X 1 ¾” and displays a United States Air Force Security Forces badge on the obverse and the Great Seal of the United States on the reverse. Each bar is comes in an acrylic snap tight holder to protect it. This large United States Air Force Security Forces Commemorative Challenge Bar would make a wonderful addition to your collection or a great gift for the United States Air Force Veteran in your life! The United States Air Force Security Forces are the protection and military police of the United States Air Force. Security Forces, or S.F., were formerly known as Military Police (M.P.), Air Police (A.P.), and Security Police (S.P.). This extremely popular privately minted bar is not an official government issue, but it is a privately minted commemorative issue that is clad in 99.9% pure premium 24K Gold and brilliantly colorized. This bar is a high quality collectable. Photos show front and back views. These stunningly beautiful bars are just $15.00 each!