ARAK-21A(R) Features Components of the ARAK-21A(R) Upper Receiver: The ARAK-21A(R) is a gas piston actuated, complete upper receiver assembly designed to seamlessly interface with the standard AR-15 platform. The total extent of the interface is simply the take down pin, and the pivot pin. The new ARAK-21A(R) upper receiver offers you all its features with no change to your current lower receiver and can be installed in less than one minute with no tools. Your ARAK-21A(R) upper receiver will be shipped to you with one "Barrel Assembly Unit" (BAU), or two, depending on which package you purchase. The BAU is comprised of the barrel, gas block, muzzle brak Mfg: Faxon Firearms