{HEAD ~ an outer sealing member} extending from ends of the towers and which covers {TAIL ~ the two openings}, and 
covers
{ HEAD ~ an outer sealing member } extending from ends of the towers and which covers { TAIL ~ the two openings } , and
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH