There are provided an improved product consisting of an elongated non-metallic sheet having a metal embedded therein or attached thereon over the entire length thereof and method and apparatus for producing the same. In particular, the product having the metal forming a wire arranged in a zigzag fashion may preferably used for covering and protecting joints of steel pipes in oil pipeline or cables. In the improved product, the sheet is trimmed on each of the longitudinal sides along a line a predetermined lateral distance outwardly or inwardly from the outline of the periphery of the corresponding side of the metal. In a case of the wire in a zigzag fashion, the wire has turning ends and the outline connects neighboring turning ends.