Pen

FIG. 1 is a top, front right side perspective view of a pen;

FIG. 2 is a top plan view thereof at an enlarged scale;

FIG. 3 is a bottom plan view thereof at an enlarged scale;

FIG. 4 is a front elevation view thereof;

FIG. 5 is a rear elevation view thereof; and,

FIG. 6 is a left side elevation view thereof, the right side elevation view being a mirror image.

The broken lines in the figures illustrate portions of the pen that form no part of the claimed design.