Sierra 18-8821-1 Mercruiser Thunderbolt V8 Gen Spark Plug Wire Set Sierra replacement engine parts are designed to meet or exceed OEM requirements. This spark wire set is used on Mercruiser engines. Kit includes coil wire. Kevlar core for maximum durability and long life. Durable stainless steel wound conductor for maximum horsepower and engine performance. Premium silicone jacketing and boots for the ultimate in high temperature protection. Superior RFI suppression for the most sensitive electr