1.25" with small union bug back stamp. Small curl text reads "Copyright 1941 By United America Inc. Minneapolis, Minn. U.S.A." Couple pinpoints of age on the curl but the front remains Mint. Depicted are three Japanese planes each with a sun symbol on the side. Below is irregularly shaped white area with ten small marks representing bombs and five explosion designs. We thought perhaps the white shape represented the island of Oahu but that doesn't quite compare so we are uncertain as to the significance of this white area on the button. Only example we recall seeing.