SET OF 3 PERFORMANCE SPARK PLUG Mercury 135 Optimax V6 all KRT11DOR15LGSRTZ7 1. Higher HP and torque by up to 3 % 2. increased economy by up to 5% 3. 360 Firing Technology 4. Improved acceleration by up to 15 % 5. 5 UP TO 600 HOUR LIFESPAN