United Defense M42

The MP5K is a compact version of the famous Heckler & Koch MP5 submachine gun chambered in 9x19mm. The K stands for Kurz, German for short, with the weapon being significantly shorter than the standard MP5. It uses a roller-delayed blowback action inherited from the HK G3 rifle. The MP5K has a 115 mm barrel and a vertical foregrip instead of a standard handguard. It is designed for concealed carry by plainclothes security personnel and special operations forces.

The Bergmann MP-18 is the world's first practical submachine gun, designed by Theodor Bergmann in 1918. It was developed for the German Army during World War I to provide infantry with a high volume of close-range firepower. The MP-18 fires the 9x19mm Parabellum cartridge from a 32-round drum magazine. It uses a simple blowback action with an open bolt. The MP-18 established the basic concept of the submachine gun that would dominate close-quarters battle for decades.

The Sa vz. 25 is a variant of the Czechoslovak vz. 23 submachine gun featuring a folding metal stock instead of the fixed wooden stock on the vz. 23. It was designed for use by paratroopers, vehicle crews, and special forces who needed a more compact weapon. The vz. 25 shares the same telescoping bolt action and receiver as the vz. 23. Its folding stock folds to the side, reducing overall length for storage and transport. The weapon is chambered in 9x19mm Parabellum and feeds from a magazine inserted in the pistol grip.