The Shieldships resembled giant umbrellas and were designed to repel the dangerous heat rays of the system's star. They had large tubes and fins designed to vent the heat generated by the star. However, the cooling gear onboard a Shieldship needed to be replaced after every visit to Nkllon.
Any ship that traveled to and from Nkllon had to trail behind a Shieldship for protection from the star's rays or its systems and hull plating would be melted by the star. The Shieldship had an advanced slave circuit system for taking control of the ships behind it, making a quick 1 hour hyperspace jump to Nkllon. Without a slaving system, then the trip to Nkllon would have to be made at sublight speeds which would take up to 10 hours.
When Lando Calrissian's Nomad City controlled Nkllon, it was profiting with nearly 10 million credits a year. The Shieldship was designed by Lando Calrissian himself, who was inspired after witnessing Cronal's actions during the Battle of Mindor, and was constructed by Republic Engineering Corporation. Lando purchased 12 of the Shieldships which allowed for up to 3 visits to Nkllon per day.
During the Galactic Civil War, Grand Admiral Thrawn attacked Nkllon, stole Lando Calrissian's mining machines, disabled every shieldship, and disrupted communications. Had it not been for the timely arrival of Garm Bel Iblis, everyone on Nomad City would have died.
The Shieldships (lent from Lando Calrissian's base above his mining operations at Dubrillion and Destrillion's asteroid fields, which in turn were given to Han and Leia Solo) were also used to defeat the Yuuzhan Vong at their base on the planet Helska IV. The Shieldships took orbit around the enemy planet and reflected the condensation of the planet back towards itself, and froze the planet to near absolute zero. The yammosk, or war coordinator, was stopped, and the Yuuzhan Vong were utterly destroyed without the joining power of the yammosk.