FIG. 1 is a top plan view of a carbon blank showing our new design;

FIG. 2 is a bottom plan view thereof;

FIG. 3 is a top plan view showing a modified form of our new design;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a top plan view showing another modified form of our new design; and

FIG. 6 is a bottom plan view thereof.

The blanks are of conventional thickness and the dash lines and stippling represent fold lines and adhesive material.