The M400 SDI X Series is the out of the box performance solution. The X Series features a 16" chrome molly barrel with a free-floating M-LOK handguard, SIG Flatblade Match Trigger, ambidextrous bolt catch and release, Magpul SL stock, and mid-length gas system.
 
Ambidextrous Bolt Catch and Release
Low Profile Gas Block with Mid-Length System
SIG Flatblade Match Trigger
Hybrid Compensator/Flash Hider
Magpul SL Stock