HP 20 MODULAR SMART ARRAY User Manual page 23

Installing the Enclosure in a Rack
6. Loosen the locknut on the shipping bracket (1), and move the bracket to the
rearmost position on the rail (2).
7. Repeat steps 4 through 6 for the left rack rail.
8. Align the enclosure with the rails, and slide it into the rack.
HP StorageWorks Modular Smart Array 20 User Guide 3-5