The Vector series is a family of submachine guns developed by KRISS USA, formerly Transformational Defense Industries (TDI). They utilize an asymmetrical recoil mechanism and in-line design to reduce recoil and muzzle climb.
The weapon's patented action was originally designed by French engineer Renaud Kerbrat. This action, the so-called Kriss Super V system, is an articulated mechanism which allows the block and bolt to recoil off-axis into a recess behind the weapon's magazine well. The Vector series were the first to use this action; the company claims that the .45 ACP chambering was chosen in order to demonstrate that the action could "tame such a powerful round". A variant chambered for the .40 S&W caliber has since been released, as well.
The Vector's barrel is in line with the shooter's shoulder, like with the M16 and the FG 42, but also in line with the shooter's hand as with many target pistols. Combined, these factors are claimed to reduce felt recoil and muzzle climb by eliminating the distance between the shooter's hand and the bore axis.
It comes with backup iron sights and a rail for mounting optics.