{HEAD ~ another planar portion} continuously formed with {TAIL ~ said arcuate portions} and matched to the other flat portion of said elongated mating member, 
{ HEAD ~ another planar portion } continuously formed with { TAIL ~ said arcuate portions } and matched to the other flat portion of said elongated mating member ,
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH