FIG. 1 is an upper front right perspective view of a marker showing my new design;
FIG. 2 is a front elevation view thereof, with the rear elevation view being a mirror image of the front elevation view;
FIG. 3 is a right side elevation view thereof;
FIG. 4 is a left side elevation view thereof;
FIG. 5 is an enlarged top plan view thereof; and,
FIG. 6 is an enlarged bottom plan view thereof.
The broken lines shown on the top and the bottom of the marker in FIGS. 1, 5, and 6 illustrate environment and form no part of the claimed design.