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