With the signing of the Antarctic Treaty, the Zaku II C-Type was upgraded into the MS-06F Zaku II. The C-Type had been heavily shielded and strongly armored to resist nuclear radiation, which had made it much heavier. However, since the Antarctic Treaty prohibited such weapons, the C-Type was removed of nuclear radiation shielding and designated the F-Type Zaku II. The F-Type would quickly become the definitive version of the Zaku II, and all future variants would begin from the F-type as a baseline. The Principality of Zeon saw great potential within the unit for having it perform in various mission roles. The Zeon Military forces produced successful designs, decent designs, and utter failures from the basic Zaku II design. Vice Admiral Dozle Zabi had his own custom Zaku II, which he took out into the Battle of Loum. His MS-06F Zaku II had ornate engravings and markings, double shoulder spiked armor, and lastly, a gigantic Heat Hawk. Even the youngest Zabi son, Garma Zabi had his own Zaku II, the MS-06Fs Zaku II. This slight variation of the Zaku II designed featured twin 40 mm Vulcan guns. However, he is not known to have used it in battle. The Zaku II was eventually replaced by the MS-07B Gouf for ground combat. With the debut of the MS-09 Dom and the MS-09R Rick Dom, the Zaku II was largely regarded as obsolete and the MS-09 became the new frontline mobile suit. Lastly, the MS-14A Gelgoog had all but sealed the Zaku II's fate due its high-performance and ability to use beam weaponry. However, despite the fact that Zeon had developed more powerful mobile suits, they also produced several variations of the Zaku II as the war continued. This is sometimes justified by describing the Zaku as being easier to pilot than other, more powerful mobile suits.