I'm also curious on if I can use a regular 64 gb. sd card with it or if it has to be a special sort of sd card ?
I have a 521 which I love. At its' current price point it is a smart phone that is very hard to beat. The only thing missing is a front facing camera which I wouldn't likely use much anyway.
As far as the SD card is concerned the only thing is it must be a micro-SD other than that the faster the better, class 1 through 10 (10 is now commonly referred to as U1 or UHS 1 (Ultra High Speed).
With only 8 gigs native storage the SD card is handy for storing pictures and music and such locally.
This is the one I currently have in my 521
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