HP ProLiant DL560 Gen11 User Manual page 83

2. Install the server into the rack:
a. Insert the inner rails into the slide rails (callout 1).
b. Slide the server into the rack until the chassis ears are flush against the rack posts (callout 2).
3. Open the chassis ears (callout 1), and then tighten the shipping screws (callout 2).
HPE ProLiant DL560 Gen11 Server User Guide 83