When it is desired to improve the performance of {HEAD ~ a given shape} of {TAIL ~ insulator} by the incorporation of barriers in accordance with the present invention, such barriers may in some cases conveniently be incorporated initially, during the construction of the insulator 
When it is desired to improve the performance of { HEAD ~ a given shape } of { TAIL ~ insulator } by the incorporation of barriers in accordance with the present invention , such barriers may in some cases conveniently be incorporated initially , during the construction of the insulator
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH