The ornamental design for a visor for caps, as shown and described.
FIG. 1 is a perspective view of a visor for caps showing my new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom plan view thereof;
FIG. 4 is a right side view thereof; and,
FIG. 5 is a left side view thereof, the broken line showing the cap in the
figures is for illustrative purposes only and forms no part of the claimed
design and the stripping represents a contract in color and texture.