HP ProCurve 2520G-PoE Series Installation And Getting Started Manual page 30

Installing the Switch
Installation Procedures
Install 12-24
screws
2-10
2. Hold the switch with attached brackets up to the rack and move it
vertically until rack holes line up with the bracket holes, then insert and
tighten the four number 12-24 screws holding the brackets to the rack.
Figure 2-4. Mounting in a rack