Fits all standard Holley, Demon, Edelbrock, Carter 4150 type carb flanges. Center to center of bolt mounting bolt holes are 13.250" and center to center on the carburetors are 12.562". Carb. adpt. is 2.625" thick from blower mounting surface to carburetor mounting surface. The adpt. is show polished and all gaskets and mounting hardware to bolt to the supercharger are included.