When the Principality of Zeon military deployed its new MS-06R-1 Zaku II R-1 for field testing during the One Year War, comments and feedback on the test unit’s design came back from pilots on how to improve the mobile suit even more. These ideas were incorporated into another upgrade, the MS-06R-1A. The R-1A type saw minor engine problems corrected, and its additional propellant tanks were replaced with removable fuel cartridges, making the R-1A faster to refuel during battle. A total of 56 new R-1As were produced, with half of the original 22 R-1 units upgraded into R-1A-types. Despite the increased performance and its popular design, however, the R-1A unit was deemed too expensive to produce – and too difficult for green pilots to handle. Production on the R-1A-type was halted, with the produced units becoming desired status symbols among Zeon mobile suit pilots. The R-1A-type was used by many famous Zeon aces, including the Black Tri-Stars team of Gaia, Mash and Ortega, as well as Eric Mansfield of the Home Defense Corps, and Masaya Nakagawa, stationed at the A Baoa Qu asteroid base. The units used by the Black Tri-Stars survived the war and were used by Char Aznable and two other pilots upon his return to the Earth Sphere in early U.C. 0083. Their distinctive color schemes created the momentary impression with EFF pilots that the Black Tri-Stars were still alive.