aot Armed Ops Tactical Rifle HK FRONT Folding Back up Iron Sight Buis Flip up Folding Ar15 Battle Sight is designed to work on same-plane rail systems only The locking system ensures your sights will remain up and zeroed in To fold the sight just simply press the release button located on the left side Features a zero-canting system, good quality back up sight MIL-SPEC Type III Hard Coated T6 Aircraft Aluminum construction