A roll cage does two unrelated things: protect in the event of a rollover and stiffen the body. On a convertible, which has lost its roof and a significant amount of rigidity, the difference is noticeable from the first bump - less shaking through the windscreen, with the front axle staying aligned with the rear.

These are styling and stiffening roll cages, designed for road use and open track days. A timed competition under a racing license requires a roll cage approved by the governing federation, along with its documentation: this is not the same part.