The ornamental design for a cable sheath, as shown and described.
FIG. 1 is a perspective view of a cable sheath, which is circular in cross section.
FIG. 2 is an enlarged partial view of FIG. 1; and,
FIG. 3 is an additional, enlarged partial view of FIG. 1.
The enlarged partial views are shown for convenience of illustration. The present invention is the design of the exterior of the cable. The interior features are shown with broken lines, which form no part of the claimed design. Color is intended to be a feature of the present design wherein the claim is a gold tone sheath with gold speckles. The symbol representing gold is shown in a portion of FIG. 3, it being understood that it is uniformly continuous over the entire surface of the claimed design.