Sig Sauer M400 SDI X, Semi-automatic Pistol, AR, 556NATO, 11.5 Threaded Barrel, Anodized Finish, Black, Pistol Brace, 30 Rounds, 1 Magazine PM400-SDI-11B-BLK The M400-SDI X Pistol has been developed with the input from the professional instructors at SIG SAUER Academy. Building upon their decades of experience and countless hours of instruction, Sig developed the M400-SDI X Pistol to meet the highest standards of performance and reliability. With fully ambidextrous controls including a bolt catch/and release unique to the M400-SDI lower receiver, the M400-SDI X Pistol delivers advanced performance for both left & right-handed shooters and makes transitional shooting easier than ever.