Plank unit

FIG. 1 is a perspective view of a plank unit showing a first embodiment of our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left view thereof;

FIG. 5 is a right view thereof;

FIG. 6 is a top view thereof;

FIG. 7 is a bottom view thereof;

FIG. 8 is a perspective view of a plank unit showing a second embodiment of our new design;

FIG. 9 is a front view thereof;

FIG. 10 is a rear view thereof;

FIG. 11 is a left view thereof;

FIG. 12 is a right view thereof;

FIG. 13 is a top view thereof;

FIG. 14 is a bottom view thereof;

FIG. 15 is a perspective view of a plank unit showing a third embodiment of our new design;

FIG. 16 is a front view thereof;

FIG. 17 is a rear view thereof;

FIG. 18 is a left view thereof;

FIG. 19 is a right view thereof;

FIG. 20 is a top view thereof;

FIG. 21 is a bottom view thereof;

FIG. 22 is a perspective view of a plank unit showing a fourth embodiment of our new design;

FIG. 23 is a front view thereof;

FIG. 24 is a rear view thereof;

FIG. 25 is a left view thereof;

FIG. 26 is a right view thereof;

FIG. 27 is a top view thereof; and,

FIG. 28 is a bottom view thereof.

The plank unit is shown with a symbolic break in its length and width. The appearance of any portion of the article between the break lines forms no part of the claimed design.