This genuine McCormick 3666840M1 fuel tank cap is an essential component for a wide range of McCormick agricultural tractors. It ensures a secure and tight seal for the fuel tank, effectively preventing fuel contamination from debris and moisture, as well as minimizing fuel evaporation and loss. This OEM part is designed to fit various McCormick models, including those from the C, CX, MC, MTX, T-MAX, X10, X4, X5, X6, and X7 series, maintaining the integrity of the fuel system.