Universal Dual Use Plastic Wall Plug Nylon Anchor for Solid Hollow Substrate Expansion Insert Wall Mounting Product Description The Universal Dual-Use Plastic Wall Plug eliminates the need to stock separate anchors for solid and hollow walls. Its patented split-body expansion design combines two anchoring mechanisms in a single nylon PA6 plug: in solid substrates (brick, concrete), the screw drives through the plug causing standard radial expansion against the borehole wall;