11/16” with design of semi circles on brass rim surrounding Mint ferrotype with name above portrait “G.B. M’Clellan.” Listed as Sullivan GMcC 1864-59. Reverse once had thin brass pin with narrow brass tab at bottom to hold it in place. The tab is gone as well as the original pin but long ago a ½” vertical stick pin was neatly soldered into position. Overall VF with essentially Mint emulsion surface. Scarce.