{HEAD ~ Two collars} are connected to {TAIL ~ two distal ends} of the two end caps and two ends of the casing 
{ HEAD ~ Two collars } are connected to { TAIL ~ two distal ends } of the two end caps and two ends of the casing
HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH