{HEAD ~ The igniter} 2 wherein {TAIL ~ said gap filler} has a relative permeability of not greater than 15 
wherein
{ HEAD ~ The igniter } 2 wherein { TAIL ~ said gap filler } has a relative permeability of not greater than 15
HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH