Sony DDU100E - Manual (Page 16)

16 Installing the Drive Unit in Your Computer
Mounting the Drive Unit
If mounting rails are necessary, attach them to the drive in unit the
same way as your floppy disk drive and slide the drive unit into the
lower drive bay. If mounting rails are not required in your system,
fasten the drive unit in place with mounting screws.
Slide the drive unit into the lower bay.