Mr. Gasket Air Cleaner Spacers are designed to raise your air cleaner in order to solve clearance problems with throttle or choke linkage. They also can allow fitment of aftermarket air cleaners in certain applications. For example GM Quadrajets choke horn or carb necks have a notch in the flange which can prevent many aftermarket air cleaners from fitting. Because this spacer does not need to index on the neck, it inexpensively and easily solves this problem. Installs simply, it just sits on top of the carb between it and the air cleaner. You may need a longer air cleaner stud depending on the height of the spacer you use and the design of the air cleaner. It's also recommended you make sure you have enough hood clearance to raise the air cleaner. The 5-1/8 inch inner diameter fits most Holley, Carter, Edelbrock and Quadrajet 4-barrel carburetors. Will not fit 4500 series or Holley Dominator models.