It's really a type of threaded insert. There are 2 varieties: a person is created to sort a bulge on the back side on the panel to be a screw is tightened in its threads. The other is likewise drawn in using a screw, but is drawn to the sleeve https://cz-grips-wood30628.pointblog.net/5-essential-elements-for-inserts-for-metal-alloy-67817076