Dell VersaRails Guide D'installation page 27

4
Install the stiffening bracket between the back ends of the slide assemblies and secure
the bracket with a 12-24 0.5-inch pan-head Phillips screw on each slide assembly
(see Figure 1-16).
Figure 1-15. Brackets Prepared for Center-Mount Installation
mounting flange
shoulder washer (2 per bracket)
nut (2 per bracket)
1-25
Rack Installation Guide