More preferably, {HEAD ~ the valve member} is in {TAIL ~ the form} of a generally resilient annular ring 
More preferably , { HEAD ~ the valve member } is in { TAIL ~ the form } of a generally resilient annular ring
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH