Also shown are the exterior surface 23 of the top portion 7 and {HEAD ~ the exterior surface} 24 of {TAIL ~ the bottom portion} of the housing 
Also
Also shown are the exterior surface 23 of the top portion 7 and { HEAD ~ the exterior surface } 24 of { TAIL ~ the bottom portion } of the housing
REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH