A cage nut or caged nut or captive nut or clip nut consists of a (usually square) nut in a spring steel cage which wraps around the nut.
Sometimes it is hard to find them or the price is too expensive so to be prohibitive their buying.
But is easy to made the most of them and the cost is only the price of a simple nut.
https://youtu.be/Uysn7dTbLtk
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