The upper inside surface and {TAIL ~ the lower inside surface} of the housing define {HEAD ~ a group} of slots and a rear wall of the housing defines a plurality of openings 
The upper inside surface and { TAIL ~ the lower inside surface } of the housing define { HEAD ~ a group } of slots and a rear wall of the housing defines a plurality of openings
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH