The Power Guard Enhancement System was a research project conducted by the Galactic Republic during the Cold War on Nar Shaddaa. Fearing that the Jedi Order was on the verge of extinction following the Great Galactic War, the Republic Senate authorized the establishment of a black ops research program on Nar Shaddaa to develop super-soldiers using a combination of cybernetics and adrenal stims. These Power Guards would be deployed to counteract the Sith on the battlefield in the event that no Jedi were available.
It was based on Nar Shaddaa due to the illegal nature of the research and was so secret that not even high ranked officers in the Republic military who oversaw the project knew where the project's headquarters were located. There was no shortage of volunteers for the project, mostly composed of refugees egging for payback against the Sith Empire.
Following the theft of the Republic's superweapon plans by Sith Lord Tarnis, Lord Sadic seized control of the project, using its technology to augment and control hapless victims before it was shut down by the efforts of the Hero of Tython.
There were three models of Power Guards, Mark I, Mark II and Mark III.