MR43T spark plugs come pre-gapped as specified by your engine manufacturer. Use only the spark plug listed in your engine owner’s manual. Using the wrong plug can reduce optimum performance reduce fuel economy or cause damage to your engine. Spark plugs are easy to change with common spark plug sockets. The AC Delco ribbed suppressor seal extends resistance and prevents spark “flash over” and misfire. They feature a copper-core center electrode that helps provide improved heat transfer to the tip giving you the reliability you re looking for while improving its resistance to low-speed carbon fouling. The AC Delco exclusive hot-tip insulator heats fast and fires hot to promote longer electrode life for miles of dependable performance. The Quicksilver brand is the leader in delivering uncompromising engine oils parts and accessories to the marine industry for over 65 years. Quicksilver is the premier supplier of Mercury Marine original equipment replacement engine parts oils and accessories but also works to serve all original equipment brands in the marine and powersports industries. It has earned a loyal following by providing the highest quality products that are tested through some of the most rigorous environments and testing procedures. No aftermarket company comes close to the level of research and design as Quicksilver; buying Quicksilver is buying performance protection and peace of mind.