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