U9-C4, also known as Ceefor, and given the moniker "Flat Top" by Colonel Meebur Gascon, was a somewhat apprehensive masculine astromech droid belonging to Thongla Jur, a Jedi Order member during the Clone Wars. He became a part of D-Squad, a team formed to acquire a Separatist encryption module, and underwent modifications to incorporate a potent laser cutter into his frame.
Around the year 20 BBY, U9-C4 was selected for membership in D-Squad and was placed under the leadership of Colonel Meebur Gascon, who displayed minimal regard for droids and viewed them merely as possessions. Prior to their mission, the droids were sent to the Parwan doctor Gubacher for enhancements needed for their mission on the dreadnought. Ceefor received a laser cutter that, while capable of slicing through almost any substance, necessitated a fixed position due to the laser's strong kickback. After the team successfully boarded the dreadnought, Gascon instructed Ceefor to utilize his laser to induce a brief power outage in the comm-vault's power system. However, the droid neglected to secure himself beforehand, and the recoil propelled him into the wall behind him, although he accomplished his objective. Later, after M5-BZ malfunctioned while trying to unlock the vault door, Gascon rode atop Ceefor's head for the remainder of the mission.
Following the successful retrieval of the encryption module, D-Squad encountered a cluster of icy comets and were compelled to make an emergency landing on the planet Abafar, eventually discovering the settlement of Pons Ora. After obtaining assistance from the amnesiac clone trooper "Gregor," Ceefor and his fellow droids commandeered a shuttle from a nearby landing zone and departed the planet.
Ceefor and the team later managed to board the Renown, which was in orbit with the encryption module, only to discover that the ship had been seized by the Separatists. Their plan was to utilize it (along with the substantial supply of rhydonium on board) to detonate a Republic space station within the Carida system during a Republic strategy conference. Fortunately, D-Squad successfully thwarted the scheme, and subsequently, Ceefor and the other droids were assigned to the same platoon as Gascon.