The German successes at the beginning of the Second World War were known as "Blitzkriegs", and demonstrated the effective use of close support air power. However; when the war entered a new phase, with the allies having air superiority over the European continent, the Germans were forced to develop, and make use of, many different anti-aircraft weapon systems. Most of these comprised the mating of an anti-aircraft gun to the chassis of a proven military vehicle. One of these variations was the uniquely styled Sd.kfz. 7/2. The formidable Flak 37 anti-aircraft gun was mated to the highly versatile 8 ton semi track produced by the Krauss-Maffei firm. The basic construction of this semi track was a remodeled ladder frame from a regular truck; a front suspension of transverse leaf springs; and a rear suspension of leaf springs and torsion bars matched to the compound track rollers, typical of German military vehicles. Armor plate was added to the radiator and driver's cab from mid 1943 onward. The Flak 37 gun was an improved Flak 36 with a new, clockwork powered sight, and was the standard defense against low-flying aircraft throuhout the war. A total of 123 Sd.kfz. 7/2 were produced.