"Chatter" and "Hamm" were radio communications clones who participated in the Second Battle of Geonosis.
Radio communications clones carried a radio box backpack used for communication. The backpack had a microphone, as well as a crank to power it. They also possessed retractable antennas on their helmet bumps.
Radio communications clones were originally designed to appear in the Clone Wars episode Landing at Point Rain but were scrapped. George Lucas stated that their concept was redundant, since many individuals possessed communication devices, such as comlinks.