Mr. Gasket 121 Intake Gasket Forms an airtight leak proof seal Engineered specifically for rectangular raised port big block Chevys with 2.500 inch by 1.750 inch intake ports .062 inch thick and precision die cut for exact fitment and years of trouble free service Ensures optimum torque retention ideal crush resistance and excellent sheer strength sealing with minimal clamp force yet still releasing easily every time Comes complete with block off plates and all necessary seals