HP 158222-B21 - StorageWorks Fibre Channel SAN Switch 8 Installation Instructions Manual page 12

4. Assemble the outer rails by completing the following steps:
Figure 4: Installing the outer rails (HP 9000 Series or comparable EIA rack)
12
a. Attach the left outer rail and the right outer rails to the rear mounting
brackets using (2) 1/4-20 hex nuts with captive star lock washers attached
loosely as shown in
tightened later in
Figure 4. Don't tighten them. The nuts will be
step 8.
SAN Switch Rack Mount Kit Installation Instructions