The width of {HEAD ~ the valve member} is smaller than a peripheral dimension of {TAIL ~ the openings} 
The width of { HEAD ~ the valve member } is smaller than a peripheral dimension of { TAIL ~ the openings }
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL