Each C shaped channel 18 includes {HEAD ~ a pair} of opposed generally L shaped legs 34 and an interconnecting portion 36 extending between {TAIL ~ legs} 34 
Each C shaped channel 18 includes { HEAD ~ a pair } of opposed generally L shaped legs 34 and an interconnecting portion 36 extending between { TAIL ~ legs } 34
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH