NEC POWERMATE PRO2180 Manual page 143

From the front of the system, insert the device, connector
3.
end first, into the device slot.
NOTE
cabling, do not insert a 5 1/4-inch device all the way
into the slot.
Connect the device cables.
4.
Align the holes in the device with the holes in the side of
5.
the system unit.
5-40 Installing Options
To easily access device connectors for
Attaching device rails