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