As the post says, this is just about one arm - specifically the left arm - since that was what came up next in the random build order.
This is the third and final body part that uses an Advanced MS Joint. In this case it makes up the entire arm frame:
Previous Advanced MS Joints on this kit included a small hinge for the leg and the foot assembly, neither of which felt like the old ones from the early Real Grade kits. This is the one exception. The photo above shows the piece in its original form. To make it into an arm, you have to:
- Pull out a random ball joint that ends up being tossed away
- Rotate a piece a full 180 degrees
- Bend the pieces so that they resemble the actual shape of an arm
- Rotate a small clip (You can see it on the bottom, pointing straight down) and secure it to the rest of the frame
That is what I remember having to do on my old RGs. While impressive, it is also kind of a pain, and I hope the joints do not become floppy and noodly over time.