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