Browning 12502 X-Bolt Integrated Scope Mount System Matte BlackBrowning's X Bolt integrated scope mount system is lightweight and unitizes the ring and base into a single, ultra rigid unit. To ensure the new X Bolt has the most stable mount possible, this system features an all new X Lock scope mounting system that uses four screws per base, replacing the traditional two screw system. The scope bases being secured at all four corners rather than only held at the center of the base enables more accurate placement