The Plasmite RPG is a weapon used by Jak during Jak 3. It is a grenade launcher that is a red eco-powered red mod Morph Gun weapon focusing on high-power, medium-range force. Jak received the weapon from Tess after beating the second gun course.
The design is very similar to the Scatter Gun but incorporates a series of rotating barrels. It is a grenade launcher powered by red eco and plasmite, the same substance behind plasmite bombs from the mission "Blow up strip mine eco wells". Despite its name, it is not a rocket-propelled grenade launcher, rather it shoots bombs in the form of an arc, similar to the Dune Hopper's grenade launcher.
The RPG's grenades lack the range of the yellow mods but make up for it with the ability to bounce, as well as a slight auto-tracking feature ensuring they will detonate closer to a target (not always the intended one however). It is also one of the most direct powerful weapons, ensuring a sizable explosion which can take care of the majority of Metal Heads, KG Death Bots and even Dark Makers you encounter throughout the game.
The sole downside to using the Plasmite RPG is its inefficient ammunition consumption, even with the effiency upgrade you are likely to burn through it very quickly when using it against every enemy, meaning it is best kept in reserve against particular strong ones such as troopers; as the grenade can be skillfully used to bounce into a wall and hit them in their backs, circumventing their shields.