The freshly cut floppy disk slot.
Above you can see the floppy drive with the hard drive mounted on top, with the two brackets on the left.
Here I've outlined the back fixing for the lower bracket. The front of the bracket is bolted to the expansion card fixing. Because the bracket is only fixed to the front expansion card fixing, there is a lot of movement there. So the rear bolt, which is fixed straight to the cage, is spaced to keep the floppy drive from swinging away from the front of the case.
You can see above the two bolts. The second bracket was then turned the other way up and fixed to the rear expansion card fixing. Using large washers the front of the second bracket was trapped using the spaced bolt, and the whole thing became rigid.