The NGK LKAR7C-9 93961 Nickel Copper Spark Plugs are specifically engineered for Mercury 4.6L Racing, 250R, 300R, and 450R outboard engines, offering exceptional ignition performance, extended durability, and improved fuel efficiency. This product is available in two convenient options: Set of 4 – Ideal for partial engine servicing or staggered maintenance schedules. Set of 8 – Recommended for a complete spark plug replacement, ensuring all cylinders receive fresh ignition components for maximum performance. Designed with a nickel copper core, these spark plugs enhance combustion efficiency, reduce misfires, and optimize throttle response. The trivalent metal plating provides superior anti-corrosion and anti-seizing properties, making these spark plugs perfect for harsh marine environments. Pre-gapped and engineered to meet OEM specifications, the NGK LKAR7C-9 93961 spark plugs offer a precise fit, smooth idle, and reliable starts, making them the top choice for boat owners, marine mechanics, and performance enthusiasts.