The Mr. Gasket Carburetor Adapter Kit allows you to install a square flange carburetor like a Holley 4150,4160, Edelbrock, Carter AFB, etcetera,, onto a Quadra-jet or Thermoquad 4-barrel spreadbore intake manifold. And yes, it works in reverse. Just flip it over, and it allows you to install a spreadbore carb onto a square bore intake manifold. This die-cast aluminum spacer is 3/4 inch thick with an open center. Installs very simply between the intake manifold and carburetor. Gaskets, studs, nuts and washers are included.