The system 15, wherein {HEAD ~ a midsection} of each of the longitudinal sidewalls extends towards a central region of {TAIL ~ the body} 
The system 15 , wherein { HEAD ~ a midsection } of each of the longitudinal sidewalls extends towards a central region of { TAIL ~ the body }
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL