Designed to join 2 floor coverings of the same height. Made from extruded aluminum. Screw nails included. Carpet metal installation on concrete surface suggestion: drill a hole in the concrete, insert A 3/16" X 1-1/4" Or 1/4" X 1-1/4" Wood dowel. Use the screw nails provided with carpet metals, insert into Dowel, expanding the dowel to lock in place.