No plugs needed.... Cut into concrete with a small diameter lower hole. Clean installation.... It does not damage the installation due to the tightening process, so it can be used near the edges and corners of the other material. High and low threads.... High thread of thread is a diamond cut (cut part) that cuts sharp into concrete, and the threads that provide a smooth and perfect tightening without stuffiness, providing excellent work and holding power. Rust resistant silver coating finish.... Rust and corrosion resistance is top class. Applications: For mounting concrete, mortar, blocks, bricks, wood, etc.