Despite showing much promise, development and production of the aircraft was stopped by the German occupation of Czechoslovakia.

[1] The A-300 was a twin-engined, low-wing monoplane of mixed wood and metal construction, with a retractable tailwheel undercarriage, that was intended to carry out both bombing and reconnaissance missions.

The wings were of wooden construction, while the fuselage had a chrome-molybdenum steel-tube structure, with a duralumin and wood frame covered by sheet metal making the outer shape of the aircraft.

[3] The aircraft was powered by two Bristol Mercury IX radial engines driving three-bladed propellers and rated at 610 kW (820 hp) at 4,400 m (14,400 ft).

Defensive armament consisted of three vz.30 machine guns,[a] one in the nose, one in the dorsal turret and one in the rear fuselage.