FIG. 1 is a front perspective view of a marker showing my new design;

FIG. 2 is a front perspective view thereof with the caps separated;

FIG. 3 is a front view thereof;

FIG. 4 is a rear view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a right side view thereof

FIG. 7 is a top view thereof; and,

FIG. 8 is a bottom view thereof.

The broken lines showing portions of the top and bottom in FIGS. 7 and 8 are included for the purpose of illustrating environment and form no part of the claimed design.