Heavy-duty yttrium-enhanced nickel center electrode with copper core provides a longer lasting copper core spark plug. Nickel Spark Plug. Spark Plug. 1172, 3923, 3924, 41-602, 6719, 71, 71CC, 71ECO, 739 46005 108, 739 46005, 7938, BCPR5EY, BKR5E BLYB, BKR5E S25, BKR5E, E3.48, F1000-298680-BOS, F1000-37583-BOS, F1000-37595-BOS, FR 8 DC, Q16R-U, RBI7927, RC12YC, XS3923DP, XS3924DP.