A rock-solid foundation only gets you so far. That explains why many of today's rifles ship with plastic handguards and throwaway furniture, two things not found on the SIGM400 PRO, SIG SAUER's take on what an AR-15 should be. This carbine comes with the good stuff - all of it - pre-installed. Like a free-floating M-LOK handguard, which promotes accuracy and handling. Or a quality grip and premium, 6-position buttstock with integral QD points. The M400 PRO comes standard with AMBI controls.