Product review (5 stars): Improved replacement for the weak brittle old ones.
First of all:
Do not bother with the sellers offering plastic arms only, the whole kit was needed because the original plastic was very brittle, the other parts that hold the arms in place broke in multiple places while being removed and would not have been able to be reused to install a new arm.

This kit was very fast and easy to install and much more sturdy than the original. The kit came with instructions. They even include a screw with a torx head in case you only have a phillips on hand. Also yes its the correct part to replace the upper rack adjuster, I was a little worried at first with how different it looks but they improved the design with metal arms and 2 screws to hold the cover on rather than plastic and snap on parts only, it looks like it will handle heat and chemicals from normal dishwaher use better than the originals.