Browning Mount XBOLT XLOCK 1 Matte .400 Std Height Securely mounted optics are essential to the accuracy and precision of any rifle. To ensure the new X-Bolt has the most stable mount possible it features an all new X-Lock scope mounting system that uses four screws per base replacing the traditional two-screw system. The benefits are obvious with the scope bases being secured at all four corners rather than only held at the center of the base allowing for more accurate placement of the bases on the receiver. This revolutionary new X-Lock system holds the base tighter to the rifle than ever before.