Micro sd cards are the smallest, usually used in cell phones and sometimes in certain digital cameras. 8gb is usually how big they get, although there are probably bigger ones that are a lot more expensive.

Mini SD cards are slightly bigger, and what the N810 uses. 8gb is usually what you'll find for max capacity, although there might be some bigger but a lot more expensive.

SD cards are bigger, usually used in digital cameras. N800 uses these. Capacity cap around 32 or 64 gb for SDHC.


When buying sd cards, it might also say "class 2" "class 4" "class 6" or etc. the higher class, the faster read/write speeds you get with them.

Another thread about sd cards created recently