The Kiparis is seen in the hands of Spetsnaz commonly, and available in a weapons cache in "Numbers." Attachments used often are Extended Mags or Dual Wield.
The Kiparis is the classified SMG, unlocked after buying all the other Submachine guns, so not before level 41. It has a twenty round magazine that empties very quickly. Although the recoil is very predictable (always up and to the right), burst-firing is necessary at mid to long range.
Due to its low ammo amount and high rate of fire it is recommended to have Scavenger and Sleight of Hand with the Extended Magattachment.
Interestingly, the Decoy Grenades have the same sound file to the Kiparis making them a good combination to use as some players will mistake Kiparis Gunfire for a Decoy grenade. Although, it is an uncommon weapon among most players.