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