The P90 was developed specifically as a PDW for vehicle crew members such as tank drivers. The P90 has very good power for its size and uses an SS190 round.
It features a polymer stock with downward ejection of spent cases.
In BF2, this weapon is available to the Anti-Tank class, as a second tier unlock in BF2 and BF2 Armoured Fury. It also features in BF2 Euroforce as the default weapon for the EU Army.