Available individually in 1/4" and 1/2" thicknesses, or in a kit (pictured above) which includes two spacers (one each), and four gaskets (carb studs are optional). The spacers also act as a Base Insulator to reduce heat soak (transfer of heat) to the carburetor. This keeps your carb cooler, thereby reducing vapor locks and/or other associated problems.  1/2" spacers are now custom made from solid phenolic for maximum insulation.