Neurons do not require microSD cards to work with most projects. That said,  some files (e.g., images and audio) can consume a lot of space,  and microSD cards are ideal for storing large files that cannot fit in the modules available memory. For this reason we have added an on-board microSD  reader to all of our Neuron modules. Our downloadable MicroSD card image contains everything needed to start using BrainBoardz. We support up to 128GB on our Neurons, but a 32-64GB cards or even smaller cards will also work fine. Smaller capacity microSD cards are fine  for data logging scenarios.