X2-4 was the name given to the droid metropolis located on the moon of Uffel. The original settlement on Uffel was centered around the wreckage of the ship that transported QS-2D, R4-S2, R4-J9, and their Twi'lek owners to the moon, resulting in the Twi'leks' deaths upon landing. This initial settlement was ultimately abandoned to facilitate the construction of X2-4, a larger city designed to house the droids' facilities. The spaceport of X2-4 was, in reality, a colossal droid, potentially the largest ever constructed.
The primary industries of X2-4 were the mining operations on Uffel and the manufacturing of droids. While a significant number of the droids produced on Uffel were sold to generate revenue for the city, others were integrated as new inhabitants. Given the droids' capacity for continuous work and their limited need for currency, a substantial portion of Uffel's earnings was allocated to the improvement and expansion of X2-4.
The droid city possessed robust defense capabilities. X2-4 manufactured its own series of highly skilled war droids for local defense purposes (including its leader, HG-211), and augmented these with several droid-operated space weapon platforms, designed by its creation G-8Y5. The dense, reddish-brown atmosphere of Uffel also contributed to the city's defense. In 33 BBY, an attempted assault on X2-4 was launched by four pirate ships. This event served as a successful demonstration of the defense systems, with only one of the ships managing to penetrate the surface, where its crew was swiftly neutralized by the war droids.
The droids did not bother to fully seal X2-4 from the atmosphere, so visitors conducting business in X2-4 were required to wear breath masks and pressure suits. Near the spaceport, accommodations were available for visitors, who were generally confined to the spaceport area except during officially sanctioned inspection tours.
Although Riboga the Hutt initially provided financial support for the mining operation, QS-2D later acquired Riboga's stake, thereby becoming the sole proprietor and administrator of the city. Despite this, QS-2D maintained the pretense that the city was still under the ownership of a living, but secluded, Twi'lek master known as Gor Kolomo.