NGK 3623 BPR6EFS Standard Spark Plug. NGK&';s Standard Plugs are Constructed for Longer Life and Optimum Performance. Fits Indmar, Marine Power, Mercruiser, OMC, Redline, and Vovlo Penta inboards engines and Boston Whaler jet boat engines. 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