The M400-SDI X 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-SDI X 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 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 accessories to be attached on all four sides with no effect on accuracy. The 2-Stage Matchlite Duo trigger provides an out-of-the-box crisp 4.5 - 6.5lb pull weight with a flat blade design for a precision feel. The M400-SDI X utilizes the highest quality performance coatings to ensure maximum durability and reliability.