Champion, Copper Plus spark plug. RN12YC

4-pack. (5R6A). 14mm threaded, 3/4" (19mm) long reach. Use with a 21mm spark plug socket. Copper-core center electrode with the patented SAC-9 semiconductor resistor. Spark plug comes with the patented Ultraseal™ coated shell, to help keep the spark plug body corrosion free and better looking for a longer period of time. Fits: > L79-80 B.T. (NU); Indian: 02-08 Chief/Deluxe/Springfield/Roadmaster/Vintage; 2009 Chief Classic (Brembo calipers); 2009 Chief Standard (Brembo calipers); 2009 Chief Roadmaster (Brembo calipers)