The Principality of Zeon forces had been anticipating a war of independence and thus made their preparations for the outbreak of war by mass-producing the MS-05 Zaku I. However, a few ideas for revisions were suggested based on mobility test data. The new equipment for these suits were then intended for use by the improved MS-06 Zaku II that was being developed at a rapid pace. However, since the One Year War, broke out just before the MS-06 Zaku II entered full-scale mass production, individual MS-05 Zaku I units were fitted with MS-06 Zaku II equipment and deployed in battle as a special type. One of these served as Char's personal machine.
A new type of shield mounted on the right shoulder was developed, which could protect the machine over a wider area.
Left Shoulder Armor
The mobile suit was designed to carry out ramming attacks using the armor attached to its left shoulder with spikes installed for increased damage.
A standard armament of Zaku-type mobile suits. A shell-firing machine gun, this version uses a drum magazine.
Type A1 Zaku Bazooka
Another standard weapon for Zaku-type mobile suits. It fires explosive rounds and can be stored on the rear waist armor.
Belt-Fed Machine Gun
A variation of the standard machine gun, it uses a belt-fed ammunition system that utilizes a feed mechanism mounted on the mobile suit's back. As a result, it allows for a higher ammunition count than the drum magazine type.
During Zeon's attack on the lunar city of Von Braun at the start of the One Year War, Char Aznable piloted the MS-05S.