The ornamental design for a helmet, substantially as shown and described.
FIG. 1 is an isometric view showing the front and one side of my invention;
FIG. 2 is an isometric view showing the front and other side of my invention;
FIG. 3 is an isometric view showing the back and other side of my invention;
FIG. 4 is an elevation view showing the other side of my invention;
FIG. 5 is an isometric view showing the front of my invention;
FIG. 6 is an elevation view showing the back of my invention;
FIG. 7 is an elevation view showing the top of my invention; and,
FIG. 8 is an elevation view showing the bottom of my invention.
The details shown in broken lines form no part of the claimed design.
In FIGS. 1–6, the helmet of the present invention is illustrated as it appears on the head of a person. The head is shown in dot and dash as forms not part of the present invention.