The valve member, which may be formed from a single piece, may define {HEAD ~ an enlarged portion} retaining {TAIL ~ the seal} and a stem retaining the bias means 
retaining
The valve member , which may be formed from a single piece , may define { HEAD ~ an enlarged portion } retaining { TAIL ~ the seal } and a stem retaining the bias means
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH