The ornamental design for a retainingdevice for sheets and coverings, as shown and described.
FIG. 1 is a top perspective view of a retaining device for sheets and coverings of the invention.
FIG. 2 is a top view of the retaining device for sheets and coverings of FIG. 1.
FIG. 3 is a bottom view of the retaining device for sheets and coverings of FIG. 1.
FIG. 4 is a front view of the retaining device for sheets and coverings of FIG. 1.
FIG. 5 is a rear view of the retaining device for sheets and coverings of FIG. 1.
FIG. 6 is a left end view of the retaining device for sheets and coverings of FIG. 1, with the right end view being a mirror image; and,
FIG. 7 is a left end view of the retaining device for sheets and coverings of FIG. 1, shown holding a sheet that is shown dashed that does not form part of the claimed invention.