The McCormick 81678C1 is a genuine OEM hex nut designed with a 1/2-13 UNC thread. This essential fastening component ensures secure connections across a wide range of International Harvester and McCormick agricultural machinery, including popular tractor models such as the 450, 560, 706, 806, 1206, and many more. Manufactured to original specifications, it provides reliable performance and durability for critical applications.