So-called 'Avia factory' established 1926 at Kazanluk, becoming Caproni subsidiary 1930 and building that company’s designs: KB-1 based on Ca 100 trainer, KB-2 (Ca 113) developed as armed 2-seater, KB-3, -4 and -5 all further developments, serving through Second World War. KB-11 (1941), 750-hp high-wing monoplane multirole, was original design.