Order both racks, upper and lower. The lower rack came fully “assembled”, all four sets of wheels came installed. The upper rack was a little more challenging. I had to YouTube how to remove the upper rack. The new upper rack was bare. Had to install several parts and two of them were the side support and height adjustment pieces. There no instructions and I couldn’t find anything specific on YouTube on how to remove/install these. I learned with the second one that you need to slide the height adjustment portion off first, by depressing the two stop tabs and removing it, then the other portion can be easily removed/installed on the rack.