{TAIL ~ An annular recess} is formed in an outer surface of {HEAD ~ the orifice ring} and has first and second axially spaced walls 
{ TAIL ~ An annular recess } is formed in an outer surface of { HEAD ~ the orifice ring } and has first and second axially spaced walls
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH