NGK BPR6EFS Spark PlugNGK BPR6EFS Spark Plugs are standard spark plugs that feature a copper core to promote heat dissipation and more efficient spark plug operation. Each plug has a threaded terminal for ease of installation and removal. NGK BPR6EFS Spark Plugs are constructed to promote longer life and optimal performance. They are designed to fit most popular engines including Indmar, Marine Power, MerCruiser, OMC, Redline, and Volvo Penta as well as inboards engine and Boston Whaler jet boat engines. For your convenience, NGK BPR6EFS Spark Plugs are Sold individuallyBe sure to check your engine and maintenance manual for the correct spark plug, and only use those brands that have been recommended by your engine's original equipment manufacturer. Using the wrong plug can reduce optimum performance, lower fuel economy and/or cause damage to your engine.Replaces: Mercury Marine; 33-816336Q; Specifications: Shell; Thread Size: 14mm; Thread Pitch: 1.25mm; Seat Type: Tapered; Resistor: Yes; Resistor Value: 5K Ohm; Reach: 18mm (.709"); Hex Size: 5/8" (16mm); Terminal Type: Removable Nut; Overall Height: ISO; Gap: .031" (0.8mm); Center Electrode; Material: Nickel; Type: Standard; Size: 2.5mm; Projection: Projected; Ground Electrode; Material: Nickel; Type: Standard; Quantity: 1; Torque Specs: Cast Iron: 18-25.3 lb. ft. Aluminum: 18-21.6 lb. ft.; Brand: NGK; Heat Range: 6; Longevity: 30k Miles;