Phase I clone trooper armor was the first armor designed for the usage of the clone troopers in the Grand Army of the Republic during the Clone Wars. It was widely used throughout the first half of the Clone Wars and was designed by Kaminoans with the help of Jango Fett. The armor was considered rather bulky and inflexible on the battlefield. These design issues would be addressed and improved upon in the Phase ll trooper armor.
Phase I armor could have multiple attachments, including pauldrons, kamas, rangefinders, visors, macro-binoculars, lights, bandoleers, jetpacks, and pistol holders. Most clone officers had customized armor, but some other clones did as well.