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