Neelie refers to two container transports that the Galactic Empire employed during the time of the Zaarin insurrection.
These transports were included in a small convoy that was intentionally "leaked" to the rebellious Grand Admiral Zaarin. The convoy was presented as carrying Missile Boats, but actually contained munitions. Despite this deception, Zaarin discovered the ruse and opted to dispatch a small squadron to destroy the convoy rather than attempting to seize it. This assault was unsuccessful, and the two container transports subsequently entered hyperspace.
These transports are featured within Battle 11, Mission 3 of the game Star Wars: TIE Fighter. The mission briefing indicates that they are loaded with munitions. However, within the game itself, their cargo is labeled as "Miss. Boat," implying that they are indeed carrying Missile Boats.