Darth Vader provided Galen Marek with an Imperial uniform to use during his Sith training, designated his Sith training gear. Starkiller's training gear was both simple and versatile seeing as it survived numerous training sessions and volatile missions. Starkiller used numerous homemade variants of his basic gear and had repaired his original many times over his years as Vader's apprentice.
One variant was his heavy training gear which was homemade. It gave basic protection in toxic and polluted environments. Another variant was Light training gear which weighed less then the basic training gear. It also provided more comfort in humid environments such as Felucia.
Because of the durability of Sith training gear, many of Starkiller's later gear had similar design features, such as his Jungle combat gear.