NGK - Standard Spark Plug - LFR6A-11 (3672) - 16 Pack. Stay ahead on routine service with the NGK LFR6A-11 standard spark plug in a 16 pack. NGK standard plugs are chosen by more automotive, motorcycle, and marine engine manufacturers than any other, thanks to a proven copper core and electrode design that support fast starts, consistent combustion, and long service life. This bulk pack is a practical option for multi-cylinder engines, multiple machines, or keeping spares ready for the next tune-up.. Key Features. Plug Number: LFR6A-11. NGK Part Number: 3672. Pack Size: 16. Unique copper core and electrode design for fast starts, peak performance, and long life. Triple gasket sealing process helps eliminate gas leakage past the shell. 99% highly pure alumina silicate insulator for strength and heat resistance. Solid copper core supports efficient heat transfer and durability. Corrugated ribs help prevent flash over. Cold rolled threads help prevent damage to the cylinder head during in