S4

Essfour was a R5 unit astromech droid that served the Alliance to Restore the Republic during the Galactic Civil War.

Appearances

 * Star Wars 26: Yoda's Secret War, Part I
 * Star Wars 28: Yoda's Secret War, Part III
 * Star Wars 29: Yoda's Secret War, Part IV
 * Star Wars 30: Yoda's Secret War, Part V
 * The Screaming Citadel, Part I