the rail. These shape connections prevent ever showing any exterior damage from mounting work on the sight. The proprietary rail systems use matching slide-in mount fasteners to connect the telescopic sight to the gun. Some proprietary rails also offer the possibility to tilt the sight up to 1° (60 moa; 17.5 mrad) to the left or right. Technical advantages of rail mounting systems are the reliability and robustness of such mounting solutions. Even under hard recoil there will be no play in mounts and tolerances will not change over time and hard use. The additional material due to rail on the underside of the sight's construction also adds stiffness and robustness to the sight's body. Rail interface systems For mounting telescopic sights and/or other accessories to guns several rail interface systems are available to provide a standardized mounting platform. The best known rail interface system is the standardized MIL-STD-1913 Picatinny rail or "Pic rail", also known as the STANAG 2324 rail after its adoption by NATO forces on 3 February 1995. It is named after the Picatinny Arsenal in New Jersey, where it was originally designed, tested and proposed for military adoption over other rail standards at the time. The Picatinny rail comprises a T-rail whose top portion has a flattened hexagonal cross-section, interspersed with evenly spaced transverse "spacing slots" to accommodate long horizontal screws. Telescopic sight mounting rings are mounted either by sliding them on from one end or the other; by means of a "rail-grabber" which is clamped to the rail with bolts, thumbscrews or levers; or onto the slots between the raised sections. Another older, commercially available rail system is the Weaver rail, which was designed and popularized in the 1950s by William R. Weaver (1905–1975), and was the non-standardized conceptual precursor of the Picatinny rail. The main differences between the Picatinny rail and the Weaver rail are the rail dimensions and the spacing of the cross-slots, although the Picatinny rail is backward-compatible with almost all Weaver accessories (but not vice versa). The NATO Accessory Rail (NAR), defined by the new STANAG 4694, was approved by NATO on 8 May 2009 to replace the Picatinny rail as the standard rail interface system for mounting auxiliary equipment such as telescopic sights, tactical lights, laser aiming modules, night vision devices, reflex sights, foregrips, bipods, and bayonets to small arms such as rifles and pistols. The NATO Accessory Rail is