It's a kind of threaded insert. There's two sorts: 1 is made to form a bulge over the back again facet of your panel being a screw is tightened in its threads. The other is in the same way drawn in utilizing a screw, but is drawn to the sleeve https://breastforms42961.blogstival.com/49175826/custom-cnc-turning-can-be-fun-for-anyone