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