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