Officially, the Note 2 and 3 supported up to 64gb. For some reason, Samsung still hasn't seen the need to jump to 128gb support with the Note 4. Probably because the actual amount of people who actually use that high of a capacity in their phones is so small. It's the same reason it chose to switch from USB 3.0 on the S5 back to USB 2.0 with the new Note 4. Yes, there are some people who could actually get a lot of use out of it, but Samsung probably couldn't justify the extra cost the feature would have added when only a tiny percentage of users would take advantage of it. There's always a tradeoff. However, it may "unofficially" work with 128gb micro SDs if the previous models did.
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