Kendall Howard M5 Snap-In Cage Nuts - 50 Pack - USA Made
M5 cage nuts can be used in equipment racks that have “Universal Rails.” These are the rails that have square holes punched in them, (rather than the style that has a tapped hole drilled directly in the rail). Cage nuts merely snap into one of these square holes creating a replaceable, threaded mounting hole for an M5 screw.
Using cage nuts also gives you the ability to choose different thread sizes within the same installation. This is an important point when mounting a variety of equipment from UPS devices to small network switches.