And, all are not equal. The Flak 18 and 36 are the main mulitpurpose variants. The Flak 37 was solely an AA gun and incapable of being easily used in the ground fire role, having revised data feeds and sights. The Flak 41 (the L 71 model) was largely a failure with only a few hundred being built. It had numerous issues with the carriage and barrel before these were worked out. In the end the Flak 41 saw virtually no field service with all but a few being staticly emplaced in defense of the Reich. By mid 1944 just 279 were in service. The reason the 88 saw so much service in the field had to do more with Nazi politics and improvisation thorugh necessity than by design. Almost all of these guns belonged orgainzationally to the Luftwaffe not the Heer. As such, they came under Göring's pervue. The result was that flak units got a higher percentage of motorization than many Heer units did. Göring also saw to it that flak got priority over army artillery and other users of explosives in shell production. The result of this was that more and more frequently as the war progressed it was Luftwaffe flak units that had mobility and ammunition. This meant that they became a substitute for the lack of artillery and shells many Heer units suffered from. So, the 88 became the weapon of choice through a combination of factors none of which had anything to do with the utility of the gun itself.