The coils are in the form of {TAIL ~ spirals} and extend in {HEAD ~ a predetermined direction} 
The coils are in the form of { TAIL ~ spirals } and extend in { HEAD ~ a predetermined direction }
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD