The ornamental design for slip-on footwear with zipper, as shown and described.
FIG. 1 is a front perspective view of a slip-on footwear with zipper according to the design;
FIG. 2 is a rear view thereof;
FIG. 3 is a right side view thereof;
FIG. 4 is a left side perspective view thereof;
FIG. 5 is a top view thereof; and,
FIG. 6 is a bottom view thereof.
The dash-dash lines on the surface of the slip-on footwear with zipper represent stitching that form a part of the claimed design. The design includes shaded portions that form a part of the claimed design. The shaded portions are intended to indicate that these areas may be made of a different material than the remainder of the slip-on footwear with zipper. Specific color, color contrast, pattern, or color combinations form no part of the claimed design. The alternating black rectangles within the white quadrilateral elements represent zippers that form part of the claimed design. The exact colors, color contrast, or color combinations of the zippers form no part of the claimed design. The dotted broken lines showing the sole portion of the slip-on footwear with zipper form no part of the claimed design.