{TAIL ~ an electrically conductive metallic casing} having a passageway therethrough and {HEAD ~ an interior wall}, 
{ TAIL ~ an electrically conductive metallic casing } having a passageway therethrough and { HEAD ~ an interior wall } ,
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH