From Star Wars: The Old Republic Wiki
Cybertech is the skill to assemble droid armor, earpieces, grenades, armoring, mods, ship upgrades and miscellaneous gadgets. Armoring and mods are upgrade modifications that augment combat ability. Earpieces are external mini-computers that are worn on or near the ear. They enhance combat prowess by giving audio and visual feedback to the wearer or though direct neural feedback via an external nerve relay. Cybertechs can reverse engineer their crafted items, except grenades, and possibly discover new ways to improve their creation.