{HEAD ~ A light source} 14 wherein {TAIL ~ said helical portion} turns through an angle of at least about 720° 
wherein
{ HEAD ~ A light source } 14 wherein { TAIL ~ said helical portion } turns through an angle of at least about 720 °
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH