Compatible with 4 barrel carbs with a square bore base like the Holley 4150/4160, Barry Grant, Carter and Edelbrock,that are used on many Small/Big Block Chevy, Ford and Chrysler Mopar engines. Package includes bolts, washers, nuts and 2 washers 2" total height Phenolic material is a type of plastic resin which has excellent insulating properties,Made of phenolic resin and engineered to reduce heat transfer from the intake manifold to the carburetor that provides a denser air/fuel mixutre for increased power and efficiency. GSKMOTOR specializes in providing high-performance repair and replacement parts for various automobiles, we support 30 days returns and exchanges. If you have any questions, please feel free to contact us, we will solve it for you as soon as possible, customer satisfaction is our unremitting pursuit.