E3.18 diamond fire spark plug. Lifetime guarantee. More power, efficiency & fewer emissions. Replaces champion n4c, n5c, n7yc, rn4c, rn5c, rn7yc, replaces ngk b4es, b5eb, b5es, bev, b6eb, b6eb11, b6es, b6es11, b6eb, b7eb, b7eb11, bp7es, bp7es11, bpr7es, bpr7es11, br4es, br5eb, br5es, br6eb, br6eb11, br6es, br6es11, br7eb11, bur7ea11, bur7eb11, replaces autolite 403, 404, 4055, 4056 & xst4055.