The Panzer
The Panzer III was built by Daimler-Benz, and the A models were first produced in 1937. The first mass production version was the Ausf F, which entered service in 1939, just in time for Poland.
The Panzer III was upgunned and armor added due to the experiences in Russia in 1941 and ‘42. The Ausf J, the model preceding the L, was equipped with the 50mm KWK L39/60 gun, which could penetrate the T-34s front armor at ranges under 500 meters.
The L had the same armament, but the armor was increased to 50mm, with 20mm plates on the front and rear. This made the L pretty safe from the T-34 at longer ranges, but the KV-1 could still put it in the hurt locker. Also, with lighter side armor, even anti-tank rifles could penetrate from closer ranges at the flanks. The Ausf M was often equipped with side skirts for the hull and turret.