These are supplemental engines to the E320 Warship Engine, usually found in clusters. Though ideal for course correction in space, they provide extra thrust in an atmosphere. However, without the main E320, these engines cannot assist a vessel as large as most large Warships to achieve escape velocity. They're easily destroyed by sustained weapons fire, but the wake of their thrust may impede weapons.
Secondary propulsion for giant warships. Has good power and is useful for changing course in outer space.