Quicksilver 8M0189609 - NGK BKR7EQUP spark plugs for 383/409 aluminum headsThe NGK BKR7EQUP standard plugs come pre-gapped as specified by your engine manufacturer. It is always recommended to check the gap before installation. Use only the spark plug listed in your engine owner?s manual. Using the wrong plug can reducing optimum performance, reduce fuel economy or cause damage to your engine. Spark plugs are easy to change with common spark plug sockets. The NGK pure alumina silicate ceramic insulator provides superior strength, reduces breakage and better heat transfer. The Ribbed Suppressor Seal extends resistance and prevents spark ?flash over? and misfire plus the triple seal helps prevent leakage.Key Product Features NGK BKR7EQUP plugs are pre-gapped to your engine manufacturer?s specifications; NGK BKR7EQUP features a platinum center electrode, copper core to aid in heat removal, and pure alumina silicate ceramic for superior strength and heat removal; Check your engine owner?s manual for the correct spark plug and use only the plug as recommended by your engine?s original equipment manufacturer; Replace all the engine plugs at the same time; Application Information: