{HEAD ~ The stem retaining ring} contacts the groove rear wall when the valve stem is in {TAIL ~ the second position} 
{ HEAD ~ The stem retaining ring } contacts the groove rear wall when the valve stem is in { TAIL ~ the second position }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL