No plug needed: Cut into concrete with a small diameter lower hole. Clean Installation: This product 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 thread: High thread of screw thread with diamond-cut (cut-off) that cuts sharp into concrete, and the threads that provide a smooth and perfect tightening without any stuffiness, providing excellent work and holding power. Applications: For mounting concrete, mortar, blocks, bricks, wood, etc. www.iifas.jp