The first and second elements are capable of being pivoted between {HEAD ~ the closed condition} opposing {TAIL ~ the upper surface} and the open condition splayed away from the upper surface 
opposing
The first and second elements are capable of being pivoted between { HEAD ~ the closed condition } opposing { TAIL ~ the upper surface } and the open condition splayed away from the upper surface
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH