First and second arms are pivotally attached to the base and arranged to move to a closed position adjacent the positioning means and {HEAD ~ an open position} away from {TAIL ~ the positioning} means 
away from
First and second arms are pivotally attached to the base and arranged to move to a closed position adjacent the positioning means and { HEAD ~ an open position } away from { TAIL ~ the positioning } means
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH