65a29c43_re_Sets___Performance_Products__FireCore50
[0] Outer Core [FireCore250] 100 % Stainless steel wrap. Carries 90% of voltage to the spark plugs [FireCore50] 
Copper/nickel alloy wire wrap surrounds the inner core. This low resistance metalic composition wire carries 90° of the voltage to the spark plugs. There is over 3ft of copper/nickel wire wrap per 1 INCH of core.
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FireCore50