For example in one embodiment, {HEAD ~ the valve seat} is {TAIL ~ dome} shaped with the top of the dome truncated or sliced off 
is
For example in one embodiment , { HEAD ~ the valve seat } is { TAIL ~ dome } shaped with the top of the dome truncated or sliced off
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH