This is a 1/4" phenolic carb insulator that helps prevent carburetor boiling or heat soak. This has a bore of 1-9/16" and a bolt hole distance of 2 11/16" center to center, the outside dimensions are 2-7/16" x 3-17/32" Any questions please email or call 608-637-7167 at Dashman's Hot Rod & Speed Parts.