The FN P90 submachine gun (SMG) was developed in the late 1980s as a defensive weapon for the troops whose primary activities do not include small arms - vehicle and tank crew members, artillery crews etc. Standard pistols and SMG's chambered for pistol rounds were proved ineffective against enemy soldiers, wearing amour (bulletproof) vests, so FN Herstal developed a new round with enhanced penetration - the SS190. This round looks like scaled down to 5.56mm NATO round and forces the pointed, steel core bullet to the 600-700 meters per second at the muzzle, thus being capable to defeat standard CRISAT helmets and amour vests at reasonable distances (50-100 meters). The P90 is a blowback operated, selective fire weapon. It is fed from 50-round box magazines, made from translucent polymer. The magazine is located above the barrel, with the cartridges aligned at 90 degrees to the barrel axis. Each magazine has built-in ramp that rotates cartridge to align it with the barrel prior to chambering it. The P90 controls are completely ambidextrous, with charging handles located at the both sides of the weapon, and the safety/fire mode selector is located below the trigger. The P90 also features downward ejection of the spent cases. P90 is built in bull-pup configuration, with polymer stock. P90 may be referred as a forerunner of the PDW (Personal Defense Weapon) concept that arose in last 4 or 5 years. P90 is used by Saudi Arabia, Peruan Special Forces and some special units of Thailand army, and offered for export by FN. The RIS Model incorporates the Rail Integration System which will allow the use of Rail attachments, laser sight, flashlight, etc.