What does PX4 mean in Miscellaneous?

a pistol

Px4 Storm is a semi-automatic pistol manufactured by Beretta of Italy and intended for personal defense and law enforcement use. The Px4 uses the same short-recoil, rotating barrel action as the Beretta 8000 models and uses the same trigger and safety system as the M9/92/96 series, while being completely different in design from either. Light-weight polymer construction with steel inserts, a modular trigger group, fully enclosing slide, Picatinny rail, and changeable backstrap options for the grip are a radical departure from previous Beretta designs.

Miscellaneous