The latest addition to Knight’s family of URX Rail Systems is the URX 4. This free-floating, continuous top rail is manufactured with the Keymod mounting system and is built stronger and more stable than previous designs due to the absence of a removable bottom rail. Another key feature to the URX 4 is the Integrated Barrel Nut (IBN). The IBN system torques the rail onto the weapon and allows the rail to act as the barrel nut. This design was developed to increase stabilization and provide a simpler solution that requires less specialized tools to install and maintain. A full array of modular accessories, iron sights, and panel kits utilizing the Keymod mounting brackets have been developed specifically to accompany this rail system. With the introduction of the URX 4, Knight’s Armament Co. demonstrates its continuing determination to intelligently design effective products.