Dell S5048F-ON Setup Manual page 16

To remove the two screws from each front flange ear on the switch side of the rail and
remove each latch casting, use a Torx screwdriver. Retain the latch castings for future
rack requirements. It is not necessary to remove the back flange castings.
Figure 4. Two-post flush-mount installation
2 Attach one rail to the front post flange with two user-supplied screws, item 2.
3 Slide the plunger bracket forward against the vertical post and secure the plunger
bracket to the post flange with two user-supplied screws, item 3.
4 Repeat this procedure for the second rail.
16 S5048F-ON switch installation