The percentage of crossover points of {TAIL ~ the exposed sacrificial fiber channels} is preferably {HEAD ~ 25 to 75%, most preferably 30 to 50%} 
The percentage of crossover points of { TAIL ~ the exposed sacrificial fiber channels } is preferably { HEAD ~ 25 to 75 % , most preferably 30 to 50 % }
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD