Each sidewall has upper and lower portions horizontally offset from one another with {HEAD ~ a connecting bridging member} forming {TAIL ~ an arm rest} 
forming
Each sidewall has upper and lower portions horizontally offset from one another with { HEAD ~ a connecting bridging member } forming { TAIL ~ an arm rest }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL