SIG SAUER's M400 XSeries 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, we have developed the M400 XSeries 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 XSeries delivers advanced performance for both left & right-handed shooters and makes transitional shooting easier than ever. The free-floating handguard utilizes a new steel lockup design that significantly reduces handguard deflection by providing maximum rigidity and allows for a Mfg: Sig Sauer, Inc.