The ornamental design for an electomagneticshield for a wallet, as shown and described.
FIG. 1 is a front elevation view of an electomagnetic shield for a wallet showing my new design, the opposite side being a mirror image of the shown;
FIG. 2 is a right side elevation view thereof, the opposite side being a mirror image of the shown;
FIG. 3 is a top plan view thereof, the opposite side being a mirror image of the shown; and,
FIG. 4 is an isometric view thereof.
The dot-dashed broken lines representing a wallet are for the purposes of illustrating environment and form no part of the claimed design. The evenly spaced broken lines represent removable sections and are part of the claimed design.