Image Number 3 for United States Patent #8104218.
A firearm accessory mounting rail with an integrated back up sight system including an elongated Picatinny rail having longitudinally spaced apart first and second end regions and a transverse profile. A first sight element has a visual marker substantially centrally positioned. A second sight element has laterally spaced apart visual markers. A substantially centered longitudinal channel extends along the upper surface of the rail between the first and second sight elements. The firearm may be sighted by visually aligning the marker of the first sight element between the markers of the second sight element, the visual alignment being at least partially through the longitudinal channel. The sight elements may be defined completely within the transverse profile of the rail so as not to interfere with the normal attachment of any accessories to the rail and may be adjustable for windage and/or elevation. The visual markers may be illuminated by light gathering fiber optic or tritium elements.