It was in 1934 that the German Army ordered Rheinmettal A G to develop a new 3.7cm anti-tank gun. Rheinmettal ranked beside Krupp as the biggest gun maker of Germany and already manufactured the first 3.7cm anti-tank rapid firer in 1918. In 1935, Rheinmettal finished designing the new anti-tank gun. The overall weight was 450kg. Having two rubber-tired wheels, torsion bar suspension system and two rear trail legs, the gun could be easily moved by only a few men. A gun shield of 4mm thickness was fixed for the protection of the gun crew.