The yarn is fed through a hole in the wall of {HEAD ~ the tube} from a groove on {TAIL ~ the outer surface} 
The yarn is fed through a hole in the wall of { HEAD ~ the tube } from a groove on { TAIL ~ the outer surface }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL