A6M2b Type 0 Model 21 thumb|A6M2 "Zero" Model 21 of Shōkaku prior to attack on Pearl Harbor, 7 December 1941 After the delivery of the 65th aircraft, a further change was worked into the production lines, which introduced folding wingtips to allow them to fit on aircraft carriers. The resulting Model 21 would become one of the most produced versions early in the war. A feature was the improved range with wing tank and drop tank. When the lines switched to updated models, 740 Model 21s had been completed by Mitsubishi, and another 800 by Nakajima. Two other versions of the Model 21 were built in small numbers, the Nakajima-built A6M2-N "Rufe" floatplane (based on the Model 11 with a slightly modified tail), and the A6M2-K two-seat trainer of which a total of 508 were built by Hitachi and the Sasebo Naval Air Arsenal.Francillon 1979, p. 399.
a6m2b type 0 model 21 thumb|a6m2 "zero" model 21 of shōkaku prior to attack on pearl harbor 7 december 1941 after the delivery of the 65th aircraft a further change was worked into the production lines which introduced folding wingtips to allow them to fit on aircraft carriers the resulting model 21 would become one of the most produced versions early in the war a feature was the improved range with wing tank and drop tank when the lines switched to updated models 740 model 21s had been completed by mitsubishi and another 800 by nakajima two other versions of the model 21 were built in small numbers the nakajima-built a6m2-n "rufe" floatplane (based on the model 11 with a slightly modified tail) and the a6m2-k two-seat trainer of which a total of 508 were built by hitachi and the sasebo naval air arsenalfrancillon 1979 p 399