Knight's Armament picatinny rail mounted 45 degree offset micro flip up sight set. Flip-up sight stays down out of the way when using optics, yet is easily flipped up. A robust detent holds it in the up or down position. Mounts at a 45 degree angle to allow operator to cant the rifle slightly to access the iron sights while keeping any optics mounted to the rifle. BUIS mounts to any AR-15/SR25 railed upper receiver and handguard. Rear sight is elevation adjustable without tools as is front sight. New clamp mount base is stronger than the original version.