The expansion bolts, expansion anchors or the wedge anchors , as you may want to call it is a screw like device that is predominantly used in construction businesses. They hold themselves and the objects that are fastened to them with a mechanical wedging effect that keeps them in place.  This is almost always used in all the construction works , be it a large scale construction or a small scale one. The full bodied, partial threaded and full threaded variations give more variations for different usages.