After the successful release of the MS-06R-1 Zaku II High Mobility Test Type the Zeon engineers began to receive feedback from the pilots on ways the mobile suit's design could be improved. The biggest difference from the R-1 is that the fuel tanks on the back and legs have been modified into cartridges to solve the problem of propellant consumption. In particular, those of the legs are changed into cylindrical cartridges. This not only simplifies replenishment in the mother ship, but also allows for replenishment in outer space, and a platoon equipped with this unit is to be accompanied by a Zaku equipped with refill cartridges. As a result of these changes, the MS-06R-1A Zaku II High Mobility Type has a longer operation time.
A total of fifty-six Zaku II High Mobility Types were constructed, with half of the existing Zaku II High Mobility Test Types upgraded to the R1-A model. The Zaku II High Mobility Type became a highly sought after unit by ace pilots such as the Black Tri-Stars, Eric Manthfield, Masaya Nakagawa, and Shin Matsunaga. But despite its incredible popularity and high performance, the suit was considered too difficult for rookie pilots to handle, and too expensive for mass production.
