I will install an ordinary CD-ROM to show you how 5.25” devices are to be put into those bays. Before the installation proper, you must use the plastic rails you receive with the case:
The juts on the rails fit into the screw-holes – that’s the way the rails hold on the case of the drive. You should keep them pressed to the drive with your hands as you’re inserting the drive into the bay lest the rails fall off. The drive goes into the case through the face panel and is held in place with the plastic locks in the bay. To make the fastening stiffer, the drive is also fastened with two screws on each side.
It’s all clear with 5.25” devices, but what about 3.5” drives? It’s simple. There’s a special removable basket you receive as an accessory to the system case. This basket is equipped with a low-noise 120mm intake fan and it can accommodate as many as four hard disk drives.
A hard drive is put inside this basket and fastened with screws on two sides. Then this whole basket goes through the face panel into the 5.25” bays and is fastened with plastic locks and screws, like a 5.25” optical drive. This HDD basket occupies three 5.25” bays in the case.
To place a floppy drive into the system case, you need special rails that are screwed to the floppy’s sides, and then the whole arrangement is installed in the case and is fixed with screws.