The insert is pushed forward into the open jacket which is pushed away from the opening blade permitting {HEAD ~ closure} by {TAIL ~ gravity} 
by
The insert is pushed forward into the open jacket which is pushed away from the opening blade permitting { HEAD ~ closure } by { TAIL ~ gravity }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL