Grass Valley PRS 250 RAID Storage System - Manual (Page 23)

Mounting RAID in a Cabinet
RAID Instructions 2-5
g. Slide the two clip nuts onto each front channel as shown below.
Attaching the clip nuts
You are now ready to install the chassis in the cabinet
Rail
Counting from the top of the rail, slide
clip nuts onto the 4th and 17th holes
of each front channel.