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