The T-34 was a technologically innovative design which addressed the short-comings of the earlier BT series of wheel/track tank. The T-34 was developed during the 1936-37 period, the prototype was completed in early 1939, and in September 1940 T-34 was put into series production mounting a 76mm gun. The Model 1940, the first T-34 production variant, t was armed with the L-11 76.2 mm gun, which was considerably shorter than the subsequent F-34 76.2 mm main gun of the 1941 and later models. The mantlet was also round in contrast to the more square mantlets of later models. The tank's main advantage was its simple design which made it easy to mass produce and repair. The T-34 was also small and comparibaly light, while the tank's water-cooled diesel engine minimized the danger of fire and increased the tank's the radius of action. The design overcame the technological superiority of German forces during the Great Patriotic War. Built in Ukraine in the Kharkov Steam-Engine Factory (KhPZ), the German general von Runstedt called the T-34 the 'best tank in the world' and von Kleist said it was the 'finest in the world.' The T-34 had a more powerful cannon than German tanks, a higher top speed (32 MPH versus 25 MPH), and superior sloped armor and superior welded construction. However, the German Tiger and Panther tanks outranged the T34's original 76mm gun, and subsequently a 85mm gun was mounted on a T-34 tank. The T-34/85 was a modification of the T-34 equipped with a more powerful armor and cannon. T-34/85 had a flatter turret which gave this already inovative tank design the look that all tanks adopted after the wars end. Although not equal to the German Panther and Tiger tanks, the huge numbers of T-34s more than compensated for their technological shortcomings.