The Leupold integral mounting systems (IMS) series effectively addresses the two primary challenges encountered when attaching standard riflescopes to AR-style rifles - scope height and eye relief. Ranging from the Mark 1 to the Mark 4, each aluminum IMS cantilever design attaches directly to the firearm's mil-spec 1913/picatinny rail. This configuration elevates the scope and extends it forward, thereby eliminating the necessity for risers or specialized optics with reduced eye relief. All Leupold IMS products undergo rigorous field testing and are backed by the Leupold lifetime guarantee.