Because of {HEAD ~ the gap} between {TAIL ~ the insulating ring} and the target, high cost Boron Nitride insulators are not required and low cost porcelain insulators can be used 
Because of { HEAD ~ the gap } between { TAIL ~ the insulating ring } and the target , high cost Boron Nitride insulators are not required and low cost porcelain insulators can be used
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH