{HEAD ~ Each} of {TAIL ~ the sides} has an empty space frame by outer edges of the housing side 
{ HEAD ~ Each } of { TAIL ~ the sides } has an empty space frame by outer edges of the housing side
HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH