SIG SAUER is proud to introduce the MCX-SURG (Suppressed Upper Receiver Group) Upgrade Kit. Designed to meet the highly specialized needs of USSOCOM, the MCX-SURG Kit was developed to deliver extreme performance for special operations’ units while maintaining high levels of accuracy and durability. The MCX-SURG Upgrade Kit was specifically engineered as a drop in upgrade for a standard M4A1 lower, converting any standard Mil-Spec AR rifle into a next-generation MCX. Utilizing SIG SAUER’S advanced suppressor design the MCX-SURG has been tested under Special Operations harshest, most demanding conditions, and has been proven to exceed even the most extreme durability, accuracy and sound reduction standards. The unique heat shield design of the MCX-SURG Upgrade Kit, is meant to prevent burns while still allowing the operator to maintain high rates of fire The MCX-SURG includes a complete MCX upper receiver group, direct thread Inconel suppressor, removable titanium cage, SD handguard, low profile handguard, folding stock with adapter kit, and chambered in 5.56 NATO.