It's really a type of threaded insert. There are 2 forms: just one is meant to form a bulge within the back again aspect on the panel for a screw is tightened in its threads. One other is similarly drawn in utilizing a screw, but is drawn to the sleeve https://beckettjngvk.thezenweb.com/the-smart-trick-of-threaded-inserts-for-plastics-that-no-one-is-discussing-64207210