The Neopup is chambered for 20x42-mm point-detonating grenades. It's automatics is gas operated with a rotating bolt. At least two types of grenades are developed for the PAW-20. These are High Explosive and High Explosive Incendiary rounds. In the near future there should be available non-lethal round for law enforcement forces.

Grenade has a muzzle velocity of 300 m/s. The Denel PAW-20 has an effective range of fire in 300 - 400 meters against single targets, while range against area targets, such as group of soldiers is 1 000 meters. It can defeat enemy soldiers over light cover, as well as light vehicles and stationary aircraft.

This grenade launcher has a very unusual design, furthermore it is unusual to hold and to aim, as pistol grip is located very high at the shoulder level, and is located from the right side of the launcher. There are also concerns about ejection port location, as the shells are extracted too close to the face.

The Neopup is fed from a 7-round box magazine and fires single rounds only. The Denel PAW-20 comes with a red-dot type collimating sight as standard, however other sights can be also used, as it comes with a Picatinny rail. It can be fitted with an optical or night sight depending on the situation.