{HEAD ~ The body} has a recessed portion and {TAIL ~ a plurality} of protrusion portions disposed beside the recessed portion, wherein the protrusion portions protrude from the recessed portion 
{ HEAD ~ The body } has a recessed portion and { TAIL ~ a plurality } of protrusion portions disposed beside the recessed portion , wherein the protrusion portions protrude from the recessed portion
HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH