the concave edge is adjacent to {HEAD ~ the closed bottom end} of {TAIL ~ the plastic foam conical body}, 
of
the concave edge is adjacent to { HEAD ~ the closed bottom end } of { TAIL ~ the plastic foam conical body } ,
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH