The system consists of the pistol (2-4 cartridges, laser target pointer, electronic ignition capsule), and various ammunition types.

This design aims to prevent the gun from operating properly if the round is unlawfully modified to increase its power.

There are different models of PB-4; in some, the firing mechanism is fed by a battery, on others by a piezoelectric igniter similar to those used by kitchen gas lighters.

[4] The pistol comes with five different types of shells A person shot from about 1 meter with an 18x45T Osa pistol to the temporal region of the head suffered a penetrative injury, with the bullet traversing most of the brain, reducing the victim to a vegetative state.

[5] Defenzia of Brazil manufactures the following two variants: A set of "Osa" consists of several types of cartridges, intended for self-defense (and traumatic light-and-sound) and illumination.

The pistol launcher itself generates an electric pulse to ignite the gunpowder charge.