The Spectre Carburetor Adapter comes with a universal open spacer and a 4 hole insert spacer. This adapter is designed to allow you to adapt a Holley, Edelbrock or Carter/AFB 4 barrel carburetor to a Quadrajet intake manifold. The outer plate has been manufactured with precision die cast aluminum so that the adapter is durable, fits great and looks good. The carburetor spacer is designed to increase power by raising air/fuel velocity as it enters into the intake manifold. The adapter comes with the necessary gaskets and hardware for a quick and easy installation.