Dell Z9432F-ON Setup Manual page 19

Repeat this step to attach the second inner rail to the other side of the switch.
5. Attach the outer rail to the back of the four-post rack.
Align the outer rail peg to the back of the four-post rack.
Secure the outer rail to the back of the rack using two M4 screws for each rail.
Repeat this step to attach the second outer rail to the other side of the rack.
6. Slide the inner rails into the outer rails.
Z9432F-ON switch installation 19