{HEAD ~ At least portions} of {TAIL ~ the interior surface} of the side wall and base define a cavity within the housing 
{ HEAD ~ At least portions } of { TAIL ~ the interior surface } of the side wall and base define a cavity within the housing
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH