{HEAD ~ The elbow} 1, wherein the arc of each channel section extends through {TAIL ~ approximately 90°} 
{ HEAD ~ The elbow } 1 , wherein the arc of each channel section extends through { TAIL ~ approximately 90 ° }
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL