Asus AP1720-E2 - Manual (Page 80)

Chapter 3: Installation options 3-4
6. Insert the tabs into the holes. You
may need to swing the bracket a
bit from left to right and back to
fully insert the tabs.
7. When the tabs are fully inserted
in the holes, swing the bracket to
the right until one side is flat to
the chassis.
8. Secure the bracket with two
screws in the holes indicated.
Securing the bracket with the two screws also secures the left side of
the SCSI drive cage.