a heat - shrinkable tube for use in forming a connection part for shielded polyolefin insulated electrical wires or cables . the heat - shrinkable tube comprises an integrated assembly of two cylindrical heat - shrinkable semiconductive members arranged end - to - end and surrounded and joined at the adjacent ends thereof by an insulation material . the shrink ratio of a narrow region of the heat - shrinkable tube defined by the adjacent ends and joining insulation material is smaller than that of the remainder of the tube . the adjacent ends of the cylindrical members may partially overlap each other , and a portion of each adjacent end may be folded back upon itself to produce a rounded shape for avoiding concentration of the electric field .