As Earth Federal Forces' "Project V" hasted to get their prototype mobile suits operational and mass-produced, they needed a weapon to counter the Principality of Zeon's forces. During the middle months of the One Year War, the SP-W03 space construction pods were converted into the RB-79 Ball combat units, each one had been armed with a 180 MM Recoilless Cannon. Even though this was the standard armament, there were many variations to the Ball. One variant was the RB-79K, which was armed with a pair of cannons in place of the single one. The RB-79K was also equipped with larger Manipulator arms and a Rocket-Guided Cable Wench for grappling objects and targets. One Ball pilot, Ensign Shiro Amada, became famous for using the normally-hopelessly-outclassed Ball to defeat a high-performance MS-06RD-4 Zaku II Test Type prototype operating in Earth orbit on 6 October UC 0079.