The non extension end edge of {TAIL ~ each panel} is connected to {HEAD ~ the opposing panel} by a flat connecting wall 
The non extension end edge of { TAIL ~ each panel } is connected to { HEAD ~ the opposing panel } by a flat connecting wall
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH