This Austrian Empire 25 Heller blue definitive from 1916 features the portrait of Emperor Karl I, rendered in a finely engraved style typical of wartime imperial issues. Surrounding his profile is an ornate radiating frame with the inscription KAISERLICHE KÖNIGLICHE ÖSTERREICHISCHE POST. Issued during the final years of the Austro-Hungarian monarchy, this stamp belongs to the last imperial series before the empire dissolved in 1918. Collectors value it for its distinctVengraving by A. Schirnböck, crisp typographic elements, and its strong association with the turbulent WWI era. The used example shown retains clear cancellation marks, adding historical postal character.