It's a modified Avia B.534 of the first series. Actually the teardrop canopy isn't the German/Luftwaffe invention/modification. The cockpit hood was designed by F. Novotny in 1936 for the first, second and third series of the Avia B.534 to attach it without any main changes to the airframe . It wasn't used by the Czechoslovak AF. The hoods were attached by Germans after seizing of the Czechoslovakia.