1920's 51st Coast Artillery One Of A Kind DI. Let's just start off with this is the rarest of all DI's and would be considered the holy grail to complete any Coast Artillery / Artillery DI collection. There were only two made in this size and both were given to the commander of the unit. One he attached to the grill of his vehicle and this is the one he wore. This one is one and ahalf inches tall. Heavy brass background with super deep enameled details. No hallmarks. Has a drop in type pin back catch. There is an article in one of the old ASMIC Trading Posts magazines that explains the history of this rare badge. I don't collect di's but if there was ever one I would consider keeping this it it. You will never find another one in this size as this is the only one that exists.