Cage nut

[1][2] The original design requires an insertion tool to install a cage nut into a hole.

It permits a range of choice of nut and bolt size (e.g. metric vs English) in the field, long after the equipment has been manufactured.

The nut is usually slightly loose in the cage to allow for minor adjustments in alignment.

In the case of slide-on cage nuts, the clip dimensions determine the distance from the panel edge to the hole.

There are four common sizes: UNF 10–32 and, to a lesser extent, UNC 12–24 are generally used in the United States; elsewhere, M5 (5 mm outside diameter and 0.8 mm pitch) for light and medium equipment and M6 for heavier equipment, such as servers.