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