H-D 5R6A. 14mm threaded long reach. Used with a 21mm spark plug socket. Copper-core center electrode. Spark plug comes with the patented UltrasealT coated shell to help keep the spark plug body corrosion free and better looking for a longer period of time. L78-E82 FL L78-79 FX 84-99 B.T.(excl. TC) 75-E78 FL FX (NU)