[Source] An Imperial officer's disc (or disk), was an insignia and coding device used in the military branch of the Galactic Empire since its early days. They were already worn in 19 BBY by the graduates of the first Imperial class from the military academies. Such disks contained coded identification information and consisted of a metallic stepped cone shape appearing to be three disks stacked on top of one another. Code disks were featured on the hat and belt buckle of the most high-ranking Imperial officers. Their function was similar to that of the code cylinders, which were also part of the officers' service uniform.