Their design was a modified version of the first set of lightsabers, many copies of which were used by the clones who were deemed as failures early in their training. As such, these lightsabers each contained a synthetic crystal which enabled them to produce a red blade. They were part of a second series of lightsabers that Darth Vader bestowed to the clones who progressed far through their trials.
Subject 1138's dual weapons were constructed for the purpose of training Galen Marek's clone in lightsaber combat. Subject 1138's lightsabers originally contained synthetic crystals, producing crimson blades.
