FIG. 1 is a top, rear, right side perspective view of the expansion unit showing our new design;

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

FIG. 3 is a left side elevational view thereof on an enlarged scale;

FIG. 4 is a front side elevational view thereof on enlarged scale;

FIG. 5 is a bottom plan view thereof on an enlarged scale;

FIG. 6 is a top, rear, right side perspective view of a second embodiment of our new design, the undisclosed sides are similar to those shown in the first embodiment.