a passage positioned at the second end of {HEAD ~ the housing} and traversing from the top surface to {TAIL ~ the bottom surface} 
a passage positioned at the second end of { HEAD ~ the housing } and traversing from the top surface to { TAIL ~ the bottom surface }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL