Star wars Arc (Advanced Recon commando) trooper P1 armor

Advanced Recon Commandos, also known as ARC troopers, were an elite variant of the clone troopers that served the Galactic Republic. Chosen from the ranks of the Grand Army of the Republic, the status of ARC trooper was bestowed on clones who served with distinction on the battlefield, such as CT-1409 "Echo" and CT-5555 "Fives." The training of clone cadets also served as a means for identifying particular cadets who demonstrated the potential to become future ARC troopers.

ARC troopers such as Commander CT-7567 "Rex" were trained to serve in positions of command in the Grand Army, and could also be sent on challenging assignments less suitable for standard clones. They were given their own unique armor set, which differed greatly from the standard issue kit given to the rank-and-file clone soldiers, being equipped with more components. During the early days of the Clone Wars, ARC trooper armor served as an experimental version of the Phase II clone trooper armor.