The McCormick 6680037A1 is a genuine OEM piston ring set specifically designed for various McCormick CX series tractors equipped with Perkins 1004.40T, 1004.40TA, and 1004.42 engines. This high-quality set features a 100 mm diameter and includes multiple rings with confirmed thicknesses of 3 mm, 2.38 mm, and 4 mm, providing essential sealing and support for engine combustion. Weighing approximately 0.12 kg, this piston ring set is a direct replacement for original equipment, crucial for maintaining engine efficiency and longevity.