"Platoon leaders, switch your comlinks to encrypted command frequency zero-zero-four. Have your troopers fan out. Grid search. Every building, every nook and cranny. You know what you're up against, so keep your wits about you."
―Commander Salvo to his squad[src]

004 was an encrypted communication frequency used by the clone troopers of the Grand Army of the Republic, during the final years of the Clone Wars. This frequency was used when Order 66 was issued, so that the clones could communicate with each other while searching for any surviving Jedi on Murkhana.