The McCormick 6509857M1 is a genuine spark plug designed for optimal ignition in McCormick D-series agricultural tractors. This essential engine component ensures efficient fuel combustion and reliable starting. It features a total length of 70 mm, a thread length of 12.7 mm, and a thread diameter of 14 mm, with a 21 mm key size for installation. This spark plug is a direct replacement for original equipment, providing consistent performance and durability for your McCormick machinery.