It's really a style of threaded insert. There are 2 types: one is made to form a bulge over the back facet on the panel as being a screw is tightened in its threads. One other is likewise drawn in employing a screw, but is drawn in to the sleeve https://josuelcqco.onesmablog.com/5-essential-elements-for-inserts-for-metal-alloy-66704910