At this point, {TAIL ~ tapered slits} 2 in {HEAD ~ valve body} 1 close 
At this point , { TAIL ~ tapered slits } 2 in { HEAD ~ valve body } 1 close
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH