A medium tank (22 tons) with a crew of five, the main German tank in 1940-1942. Initially it had a 37mm gun (and two machine guns), but was planned for future use of bigger guns. It participated in small numbers in the invasion of Poland, but mass production began after the beginning of World War 2, with a 50mm gun . Since the new gun was too weak against Russian T-34 tanks, a more powerful 50mm gun was installed. Later types had an even bigger 75mm gun, same as that of the Panzer IV, with 64 rounds. Production ended in mid 1943, but production of a self-propelled gun version continued until the end of the war. There were also a command tank version and other versions. A total of 15,000 were produced.