The original Shield design is fairly old but was never successfully tested until the Kushan encountered the Taiidan Seejur-class Defender within the Great Wastelands during a battle against Imperial forces. Analyzing the technology of the Seejur, Kushan Fleet Intelligence recommended an immediate update to the original Shield design.
Equipped with an upgraded targeting system and an additional bottom gimbal turret to its set, the three-pronged Shield Mk.3b was powerful enough to take on any attacking strike craft, using its targeting system and not its speed to destroy an opponent. It should be noted that defenders had a very low velocity for a fighter class ship and did not chase enemies like standard fighters instead using their excellent firing coverage and very high maneuverability, which was important for the defender in order to evade enemy fire.
Usually, all Shield pilots would focus on taking out one target at a time, hitting the enemy with bursts of highly accurate gimbal fire. Because of this, the Shield was most commonly found guarding capital ships or resource operations when corvettes were unavailable. Shields were also tough enough to be used as a last ditch defense platform against a surprise fighter attack, often deployed in the absence of larger vessels.
Shields were piloted by a rare mixture of veterans and raw recruits, both of them usually new to the challenge and responsibilities of piloting a defender.
Originally, there was a "Light Defender", which had two cannons instead of three, but it was dropped. According to Homeworld Shipyards, it may have been an early fighter developed by the Kushan on Kharak before the Scout was developed which outclassed it in every category.