Sig Sauer MPXK9KM MPX-K-9-KM: SIG Sauer SIG MPX K Unconventional design unmatched performance and familiar AR handling. The SIG MPX redefines the submachine gun category with a new level of operator safety in-field adaptability and proven reliability in the harshest environments. Completely ambidextrous the SIG MPX is great for left- or right-handed shooters with its dual-sided selector switch magazine release charging handle and bolt release. The SIG MPX operates from a fully-closed and locked rotating bolt offering enhanced reliability and safety in use. A short-stroke gas piston allows the SIG MPX to run all weights and brands of 9mm ammunition with no adjustments to the gas valve. A full-length picatinny rail allows for solid consistent mounting of optics and targeting lasers. The MPX K features a 4.5\" barrel and a short aluminum KeyMod handguard with handstop.