Dell Precision 410 User Manual page 138

bracket tabs (2)
bracket
To further ensure proper positioning of the drive in the chassis, insert and tighten
all four screws in the order in which the holes are numbered (the holes are
marked "1" through "4").
Make sure that both bracket tabs snap into place in the drive bay.
5.25-inch drive
See "Installing an Expansion Card" in Chapter 9.
Dell Precision 410 Mini Tower Systems User's Guide
10-8