the valve seat further comprising {HEAD ~ a generally flat diaphragm engaging surface} having {TAIL ~ a second surface area}, the second surface area being less than the first surface area 
having
the valve seat further comprising { HEAD ~ a generally flat diaphragm engaging surface } having { TAIL ~ a second surface area } , the second surface area being less than the first surface area
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH