C-6RR, more commonly referred to as Sixer, served as a Class-six protocol droid owned by Numen Brock, a combatant within the Balmorran resistance, circa 3642 BBY amidst the ongoing Galactic War. Positioned at Farnel Outpost located on Balmorra, he greeted the Voidhound upon their arrival in search of his owner. After Voidhound's expedition into the Okara Droid Factory, Sixer communicated to him that Brock, along with numerous other resistance members, had been taken prisoner by Imperial soldiers while on patrol, imploring the Smuggler captain to undertake their liberation.