The flip-up Monza style gas cap is a classic for a reason. As seen on race vehicles of all types for nearly a century! High-pressure die cast assembly with 62mm threads, this 2.5″ vented Monza cap pairs well with a bolt-on or thread-in billet adapter, or, with the DIY weld-in threaded steel filler neck so you can make your wildest gas tank filler dreams come true.