Dell EMC PowerSwitch Z9432F-ON Installation Manual page 17

3. Attach the inner rail to the switch.
Line up the inner rail slot with the T-stud on the switch. Push the inner rail back until it clicks into place.
4. Confirm the rack mounting hole type and choose the correct components--EIA 9.5 mm (.354 in) square hole, EIA 7.1 mm
(.279 in) round hole, or threaded hole.
For EIA 9.5 mm (.354 in) square hole racks (default setting for the outer rail):
Z9432F-ON switch installation 17