The shoulder region merges into and provides {HEAD ~ a transition} between the finish and {TAIL ~ a sidewall portion} 
between
The shoulder region merges into and provides { HEAD ~ a transition } between the finish and { TAIL ~ a sidewall portion }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL