24mm (7/8") with intact loop on the top rim edge. Front and back each have raised brass rim accented by circle of stars and the date 1868. On the front center is embossed shell portrait with text "General U.S. Grant." Silver luster on this insert is largely gone but surfaces are a nice clean brass tone. Same condition applies to the reverse side which pictures "Schuyler Colfax." Luster on the outer rim is NM. Overall rare and extremely fine.