It relates to both the design of the valve and to {HEAD ~ the method} of {TAIL ~ its manufacture} 
It relates to both the design of the valve and to { HEAD ~ the method } of { TAIL ~ its manufacture }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL