It is just a kind of threaded insert. There are two forms: one is intended to variety a bulge around the back aspect with the panel to be a screw is tightened in its threads. The other is likewise drawn in using a screw, but is drawn in to the https://at32uc3c2256c-z2zr99752.full-design.com/5-easy-facts-about-rivet-nut-described-69621670