The Five-Seven (marketed as “Five-seveN” ) is a semi-automatic pistol in 5.7 x 28mm. FN 57 Pistol is manufactured by FN Herstal.
FN 57 Pistol is also known as FN 5.7 Millimeter Pistol The weapon’s name refers to its 5.7 mm bullet diameter.
The 5.7×28mm cartridge was originally created by FN in early 1990 for use in the FN P90 personal defense weapon. The FN 57 pistol was subsequently created by FN in the late 1990 as a side arm using the same cartridge.

The weapon’s characteristics have made it popular in law enforcement SWAT roles , where criminals wearing body armor may be encountered.
For more details visit : http://en.wikipedia.org/wiki/FN_Five-seven