FIG. 1 is a perspective view of the cover showing the new design, the broken line drawing of a portion of a mouse is for illustrative purposes only and forms no part of the claimed design;

FIG. 2 is a front elevational view of the cover;

FIG. 3 is a rear elevational view of the cover;

FIG. 4 is a right side elevational view of the cover, the left side elevational view of the cover being the mirror image of the view shown in FIG. 4;

FIG. 5 is a top plan view of the cover; and,

FIG. 6 is a bottom plan view of the cover.