Hi Jody, I only measured the front and rear bars, and the two C shaped arcs - and they were 32mm. The cage and Caterham is presently at Alpha 7 Motorsport, hence unable to check. If the Cage you have is the one I'm thinking off, then that's the FIA approved one, noting the Trackday Cage is not FIA approved, hence I expect you might be better off selling what you have and getting a Trackday Cage - save you cutting away at metal. Coincidentally, I bought my Trackday cage from a guy who was removing it in orde to have a FIA Cage fitted so that he could compete in sprints/hill climbs. Best regards Chris