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