BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of one member of the apparatus according to an embodiment of the invention.
FIG. 2 is a side view of the apparatus shown in FIG. 1.
FIG. 3 is a plan view of another member of the apparatus according to an embodiment of the invention.
FIG. 4 is a side view of the member of the apparatus shown in FIG. 3.
FIG. 5 is a perspective view of the member shown in FIG. 1 showing a different arrangement of the grooves disposed on the surface of the member.