NGK BU8H surface gap plugs feature a semi-surface discharge design to improve ignition and burn off any carbon before it can build up to foul the plug 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 NGK Trivalent metal plating also provides superior anti-corrosion in the marine environment and anti-seizing for easier removal Spark plugs are easy to change with common spark plug sockets Spark plugs are easy to change with common spark plug sockets.