It is just a style of threaded insert. There are two kinds: 1 is meant to type a bulge to the again facet from the panel being a screw is tightened in its threads. The opposite is similarly drawn in using a screw, but is drawn in to the sleeve https://auto-parts41639.bloguetechno.com/5-simple-statements-about-inserts-for-metal-alloy-explained-62009007